FROM THE BEGINNING
INTRODUCTION
Ab Initio is a Latin phrase that translates to “from first principles” or “from the beginning”.
INTRODUCTION - Ab Initio is a general purpose data processing platform for enterprise class, mission critical applications such as data warehousing, clickstream processing, data movement, data transformation and analytics. - Supports integration of arbitrary data sources and programs, and provides complete metadata management across the enterprise. - Proven best of breed ETL solution. - Applications of Ab Initio: • • • • •
ETL for data warehouses, data marts and operational data sources. Parallel data cleansing and validation. Parallel data transformation and filtering. High performance analytics Real time, parallel data capture.
ARCHITECTURE Ab Initio Comprises of 3 Core components. - The Co>OperatingSystem -
Enterprise Meta Environment (EME)
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Graphical Design Environment (GDE)
Supplementary Components - Continuous>Flow -
Plan>It
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Re>source
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Data>Profiler
ARCHITECTURE
ARCHITECTURE
Applications Applications Ab Ab Initio Initio Metadata Metadata Repository Repository
Application Application Development Development Environments Environments Graphical Graphical C C ++ ++ Shell Shell Component Component Library Library
User-defined User-defined Components Components
Third Third Party Party Components Components
Ab Ab Initio Initio Co>Operating Co>Operating System System
Native Native Operating Operating System System UNIX UNIX
Windows Windows NT NT
OPERATING ENVIRONMENTS Ab Initio has been developed to support a vast variety of operating environments. The Co>Operating System and EME is available in many flavors and can be installed on • Windows NT based • AIX • HP-UX • Linux • Solaris • Tru64 Unix The GDE part of Ab Initio is currently available for Windows based Operating Systems only.
CO>OPERATING SYSTEM The Co>Operating System and the Graphical Development Environment (GDE) form the basis of Ab Initio software. They interact with each other to create and run an Ab Initio application: The GDE provides a canvas on which you manipulate icons that represent data, programs, and the connections between them. The result looks like a data flow diagram, and represents the solution to a data manipulation problem. The GDE communicates this solution to the Co>Operating System as a Korn shell script. The Co>Operating System executes the script.
ENTERPRISE META>ENVIRONMENT Enterprise Meta>Environment (EME) is an AbInitio repository and environment for storing and managing metadata. It provides capability to store both business and technical metadata. EME metadata can be accessed from the Ab Initio GDE, web browser or AbInitio CoOperating system command line (air commands). The basic situation when you work with the EME is that you have files in two locations, of two kinds: • A personal work area that you specify, located in some filesystem Essentially this is a formalized directory structure that usually only you have access to. This is where you work on files. • A system storage area This is the EME system area where every version that you save of the files you work on is permanently preserved, organized in projects. You (and other users) have indirect access to this area through the GDE and the command line. This area's generic name is EME datastore.
WELCOME BACK
FROM THE BEGINNING DAY - 2
GRAPHICAL DEVELOPMENT ENVIRONMENT GDE is a graphical application for developers which is used for designing and running AbInitio Graphs. • The ETL process in AbInitio is represented by AbInitio graphs. Graphs are formed by components (from the standard components library or custom), flows (data streams) and parameters. • A user-friendly frontend for designing Ab Initio ETL graphs •
Ability to run, debug Ab Initio jobs and trace execution logs.
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GDE AbInitio graph compilation process results in generation of a UNIX shell script which may be executed on a machine without the GDE installed
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THE GRAPH An Ab Initio application is called a Graph: a graphical representation of datasets, programs, and the connections between them. Within the framework of a graph, you can arrange and rearrange the datasets, programs, and connections and specify the way they operate. In this way, you can build a graph to perform any data manipulation you want. You develop graphs in the GDE.
THE GRAPH A graph is a data flow diagram that defines the various processing stages of a task and the streams of data as they move from one stage to another. In a graph, a component represents a stage and a flow represents a data stream. In addition, there are parameters for specifying various aspects of graph behavior. Graphs are built in the GDE by dragging and dropping components, connecting them with flows, and then defining values for parameters. You run, debug, and tune your graph in the GDE. In the process of building a graph, you are developing an Ab Initio application, and thus graph development is called graph programming. When you are ready to deploy your application, you save the graph as a script that you can run from the command line.
THE GRAPH
A graph is composed of components and flows: • Components represent datasets (dataset components) and the programs (program components) that operate on them. Dataset components are frequently referred to as file components when they represent files, or table components when they represent database tables. Components have ports through which they read and write data. Ports have metadata attached to them that specifies how to interpret the data passing through them. • Program components have parameters that you can set to control the specifics of how the program operates. • Flows represent the connections between ports. Data moves from one component to another through flows.
THE GRAPH A graph can run on one or many processors. The processors can be on one or many computers. All the computers that participate in running a graph must have the Co>Operating System installed. When you run a graph from the GDE, the GDE connects to the Co>Operating System on the runhost — the computer that hosts the Co>Operating System installation that controls the execution of the graph. The GDE transmits a Korn shell script that contains all the information the Co>Operating System needs to execute the programs and processes represented by the graph by.. • Managing all connections between the processors or computers that execute various parts of the graph • Program execution • Transferring data from one program to the next • Transferring data from one processor or computer to another • Execution in phases • Restoring the graph to its state at the last completed checkpoint in case of a failure • Writing and removal of temporary files
SETTING UP GDE Before using the GDE to run a graph or plan, a connection must be established between GDE and the installation of the Co>Operating System that you want to run your graph. The computer that hosts this installation is called the run host. Typically, the GDE is on one computer and the run host is a different computer. But even if the GDE is local to the run host, you must still establish the connection. Host Settings(On GDE, Run>Settings>Host Tab) dialog to specify the information the GDE needs to log in to the run host.
The GDE creates a host settings file with the name you specified. The host settings file contains the information you specified, such as the name of the run host, login name or username, password, Co>Operating System version and location, and type of shell you log in with.
DATA PROCESSING Generally, Data processing involves following tasks: • Collection of data from various sources. • Cleansing and standardizing data and its datatypes. • Data integrity checks. • Profiling of data. • Staging it for further operations. • Joining with various datasets. • Transforming data based on Business rules. • Conforming data validity. • Translating data to compatible types of target systems. • Loading data to Target systems. • Tying out source and target data for quality and quantity. • Anomaly, rejection and error handling. • Reporting process updates. • Metadata updation.
COMMON TASKS • Selecting: The SELECT clause of an SQL statement. • Filtering: Statements in WHERE clause of an SQL statement. • Sorting: Specifications in an ORDER BY clause. • Transformation: Various transformation functions used on the fields in the SELECT clause. • Aggregation: Summarization on a set of records (ADD, AVG, MIN etc) • Switch: Conditional operations using CASE statements. • String Operations: String selection and manipulation (CONCATENATE, SUBSTRING etc.) • Mathematical Operations: Addition, Division etc. • Inquiry: Test for attributes and content of a field of a record. • Joins: Specifications using JOIN(SQL server, ANSI) clauses (WHERE clause in Oracle). • Lookups: Getting relevant fields from Dimensions. • Rollups: Summarized data grouped using GROUP clause of an SQL statement.
COMPONENTS Components are classified based on their functionality. Following are a few important sets of Component categories.
COMPONENTS
COMPONENTS The dataset components represent records or act on records, as follows: INPUT FILE represents records read as input to a graph from one or more serial files or from a multifile. INPUT TABLE unloads records from a database into an Ab Initio graph, allowing you to specify as the source either a database table, or an SQL statement that selects records from one or more tables. INTERMEDIATE FILE represents one or more serial files or a multifile of intermediate results that a graph writes during execution, and saves for your review after execution. LOOKUP FILE represents one or more serial files or a multifile of records small enough to be held in main memory, letting a transform function retrieve records much more quickly than it could if they were stored on disk. OUTPUT FILE represents records written as output from a graph into one or multiple serial files or a multifile. OUTPUT TABLE loads records from a graph into a database, letting you specify the records’ destination either directly as a single database table, or through an SQL statement that inserts records into one or more tables. READ MULTIPLE FILES sequentially reads from a list of input files. READ SHARED reduces the disk read rate when multiple graphs (as opposed to multiple components in the same graph) are reading the same very large file. WRITE MULTIPLE FILES writes records to a set of output files.
COMPONENTS The database components are the following: • CALL STORED PROCEDURE calls a stored procedure that returns multiple result sets. The stored procedure can also take parameters. • INPUT TABLE unloads records from a database into an Ab Initio graph, allowing you to specify as the source either a database table, or an SQL statement that selects records from one or more tables. • JOIN WITH DB joins records from the flow or flows connected to its input port with records read directly from a database, and outputs new records containing data based on, or calculated from, the joined records. • MULTI UPDATE TABLE executes multiple SQL statements for each input record. • OUTPUT TABLE loads records from a graph into a database, letting you specify the records’destination either directly as a single database table, or through an SQL statement that inserts records into one or more tables. • RUN SQL executes SQL statements in a database and writes confirmation messages to the log port. • TRUNCATE TABLE deletes all the rows in a database table, and writes confirmation messages to the log port. • UPDATE TABLE executes UPDATE, INSERT, or DELETE statements in embedded SQL format to modify a table in a database, and writes status information to the log port.
COMPONENTS MULTI REFORMAT changes the record format of records flowing between from one to 20 pairs of in and out ports by dropping fields, or by using DML expressions to add fields, combine fields, or transform the data in the records. NORMALIZE generates multiple output records from each input record; you can specify the number of output records, or the number of output records can depend on a field or fields in each input record. NORMALIZE can separate a record with a vector field into several individual records, each containing one element of the vector. REFORMAT changes the record format of records by dropping fields, or by using DML expressions to add fields, combine fields, or transform the data in the records. ROLLUP generates records that summarize groups of records. ROLLUP gives you more control over record selection, grouping, and aggregation than AGGREGATE. ROLLUP can process either grouped or ungrouped input. When processing ungrouped input, ROLLUP maximizes performance by keeping intermediate results in main memory. SCAN generates a series of cumulative summary records — such as successive year-to-date totals — for groups of records. SCAN can process either grouped or ungrouped input. When processing ungrouped input, SCAN maximizes performance by keeping intermediate results in main memory. SCAN WITH ROLLUP performs the same operations as SCAN; it generates a summary record for each input group.
COMPONENTS The Miscellaneous components perform a variety of tasks: ASSIGN KEYS assigns a value to a surrogate key field in each record on the in port, based on the value of a natural key field in that record, and then sends the record to one or two of three output ports. BUFFERED COPY copies records from its in port to its out port without changing the values in the records. If the downstream flow stops, BUFFERED COPY copies records to a buffer and defers outputting them until the downstream flow resumes. DOCUMENTATION provides a facility for documenting a transform. GATHER LOGS collects the output from the log ports of components for analysis of a graph after execution. LEADING RECORDS copies records from input to output, stopping after the given number of records. META PIVOT converts each input record into a series of separate output records: one separate output record for each field of data in the original input record. REDEFINE FORMAT copies records from its input to its output without changing the values in the records. You can use REDEFINE FORMAT to change or rename fields in a record format without changing the values in the records. REPLICATE arbitrarily combines all the records it receives into a single flow and writes a copy of that flow to each of its output flows. RUN PROGRAM runs an executable program. THROTTLE copies records from its input to its output, limiting the rate at which records are processed. RECIRCULATE and COMPUTE CLOSURE components can only be used together. These two components calculate the complete set of direct and derived relationships among a set of input keypairs; in other words, the transitive closure of the relationship within the set. TRASH ends a flow by accepting all the records in it and discarding them.
COMPONENTS The transform components modify or manipulate records by using one or several transform functions. Some of these are multistage transform components that modify records in up to five stages: input selection, temporary initialization, processing, finalization, and output selection. Each stage is written as DML transform function. AGGREGATE generates records that summarize groups of records. AGGREGATE can process either grouped or ungrouped input. When processing ungrouped input, AGGREGATE maximizes performance by keeping intermediate results in main memory. DEDUP SORTED separates one specified record in each group of records from the rest of the records in the group. DEDUP SORTED requires grouped input. DENORMALIZE SORTED consolidates groups of related records into a single record with a vector field for each group, and optionally computes summary fields for each group. DENORMALIZE SORTED requires grouped input. FILTER BY EXPRESSION filters records according to a specified DML expression. FUSE applies a transform to corresponding records from each input flow. The transform is first applied to the first record on each flow, then to the second record on each flow, and so on. The result of the transform is sent to the out port. JOIN performs inner, outer, and semi-joins on multiple flows of records. JOIN can process either sorted or unsorted input. When processing unsorted input, JOIN maximizes performance by loading input records into main memory. MATCH SORTED combines and performs transform operations on multiple flows of records.MATCH SORTED requires grouped input.
COMPONENTS The sort components sort and merge records, and perform related tasks: CHECKPOINTED SORT sorts and merges records, inserting a checkpoint between the sorting and merging phases. FIND SPLITTERS sorts records according to a key specifier, and then finds the ranges of key values that divide the total number of input records approximately evenly into a specified number of partitions. PARTITION BY KEY AND SORT repartitions records by key values and then sorts the records within each partition; the number of input and output partitions can be different. SAMPLE selects a specified number of records at random from one or more input flows. The probability of any one input record appearing in the output flow is the same — it does not depend on the position of the record in the input flow. SORT orders and merges records. SORT WITHIN GROUPS refines the sorting of records already sorted according to one key specifier: it sorts the records within the groups formed by the first sort according to a second key specifier.
COMPONENTS The partition components distribute records to multiple flow partitions or multiple straight flows to support data parallelism or component parallelism. BROADCAST arbitrarily combines all the records it receives into a single flow and writes a copy of that flow to each of its output flow partitions. PARTITION BY EXPRESSION distributes records to its output flow partitions according to a specified DML expression. PARTITION BY KEY distributes records to its output flow partitions according to key values. PARTITION BY PERCENTAGE distributes a specified percent of the total number of input records to each output flow. PARTITION BY RANGE distributes records to its output flow partitions according to the ranges of key values specified for each partition. PARTITION BY ROUND-ROBIN distributes records evenly to each output flow. PARTITION WITH LOAD BALANCE distributes records to its output flow partitions, writing more records to the flow partitions that consume records faster.
COMPONENTS The departition components combine multiple flow partitions or multiple straight flows into a single flow to support data parallelism or component parallelism CONCATENATE appends multiple flow partitions of records one after another. GATHER combines records from multiple flow partitions arbitrarily. INTERLEAVE combines blocks of records from multiple flow partitions in round-robin fashion. MERGE combines records from multiple flow partitions that have all been sorted according to the same key specifier and maintains the sort order.
COMPONENTS The compress components compress data or expand compressed data: • DEFLATE and INFLATE work on all platforms. • DEFLATE reduces the volume of data in a flow and INFLATE reverses the effects of DEFLATE. • COMPRESS and UNCOMPRESS are available on Unix and Linux platforms; not on Windows. • COMPRESS reduces the volume of data in a flow and UNCOMPRESS reverses the effects of COMPRESS. • COMPRESS cannot output more than 2 GB of data on Linux platforms.
COMPONENTS The MVS dataset components perform as follows: MVS INPUT FILE reads an MVS dataset as an input to your graph. MVS INTERMEDIATE FILE represents MVS datasets that contain intermediate results that your graph writes and saves for review. MVS LOOKUP FILE contains shared MVS data for use with the DML lookup functions; it allows access to records according to a key. MVS OUTPUT FILE represents records written as output from a graph into an MVS dataset. VSAM LOOKUP executes a VSAM lookup for each input record.
COMPONENTS The EME (Enterprise Meta>Environment) components are in the $AB_HOME/Connectors > EME folder. They transfer data into and out of the EME. LOAD ANNOTATION VALUES attaches annotation values to objects in an EME datastore, and validates the annotation for the object to which it is to be attached. LOAD CATEGORY stores annotation values in EME datastores for objects that are members of a given category. LOAD FILE DATASET creates a file dataset in an EME datastore, and attaches its record format. LOAD MIMEOBJ creates a MIME object in an EME datastore with the specified MIME type. LOAD TABLE DATASET creates a table dataset in an EME datastore and attaches its record format. LOAD TYPE creates a DML record object in an EME datastore. REMOVE OBJECTS AND ANNOTATIONS allows you to delete objects and annotation values from an EME datastore. UNLOAD CATEGORY unloads the annotation rules of all objects that are members of a given category.
COMPONENTS The FTP (File Transfer Protocol) components transfer data, as follows: FTP FROM transfers files of records from a computer not running the Co>Operating System to a computer running the Co>Operating System. FTP TO transfers files of records to a computer not running the Co>Operating System from a computer running the Co>Operating System. SFTP FROM transfers files of records from a computer not running the Co>Operating System to a computer running the Co>Operating System using the sftp or scp utilities to connect to a Secure Shell (SSH) server on the remote machine and transfer the files via the encrypted connection provided by SSH. SFTP TO transfers files of records from a computer running the Co>Operating System to a computer not running the Co>Operating System using the sftp or scp utilities to connect to a Secure Shell (SSH) server on the remote machine and transfer the files via the encrypted connection provided by SSH.
COMPONENTS The validate components test, debug, and check records, and produce data for testing Ab Initio graphs: CHECK ORDER tests whether records are sorted according to a key specifier. COMPARE CHECKSUMS compares two checksums generated by COMPUTE CHECKSUMS. Typically, you use COMPARE CHECKSUMS to compare checksums generated from two sets of records, each set computed from the same data by a different method, in order to check the correctness of the records. COMPARE RECORDS compares records from two flows one by one. COMPUTE CHECKSUM calculates a checksum for records. GENERATE RANDOM BYTES generates a specified number of records, each consisting of a specified number of random bytes. Typically, the output of GENERATE RANDOM BYTES is used for testing a graph. For more control over the content of the records, use GENERATE RECORDS. GENERATE RECORDS generates a specified number of records with fields of specified lengths and types. You can let GENERATE RECORDS generate random values within the specified length and type for each field, or you can control various aspects of the generated values. Typically, you use the output of GENERATE RECORDS to test a graph. VALIDATE RECORDS separates valid records from invalid records.
COMPONENTS •
Where do the actual data files represented by INPUT FILE components reside?
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Where should the Co>Operating System write the files represented by OUTPUT FILE components, or do those files already exist?
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If a file represented by an OUTPUT FILE component does exist, should the graph append the data it produces to the existing data in the file, or should the new data overwrite the old?
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What field of the data should a program component use as a key when processing the data?
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What is the record format attached to a particular port?
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How much memory should a component use for processing before it starts writing temporary files to disk?
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How many partitions do you want to divide the data into at any particular point in the graph?
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What are the locations of the processors you want to use to execute various parts of the graph? What is the location of the Co>Operating System you want to use to control the execution of the graph?
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COMPONENTS Configuring Components: Components comprises of settings which dictates the way it impacts the data flowing through. These settings are seen and set with the following tabs on Properties window. • Description • Access • Layout • Parameters • Ports
COMPONENT PROPERTIES DESCRIPTION: • Specify Labels • Component specific selections • Data Locations • • •
Partitions Comments Name/Author/Version
COMPONENT PROPERTIES ACCESS: Specification for file handling methods. • Creation/Deletion • Roll back settings • Exclusive access • File Protection
COMPONENT PROPERTIES LAYOUT: •
The locations of files.
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The number and locations of the partitions of multifiles.
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The number of the partitions of program components and the locations where they execute.
A layout is one of the following: •
A URL that specifies the location of a serial file
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A URL that specifies the location of the control partition of a multifile
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A list of URLs that specify the locations of: • The partitions of an ad hoc multifile • The working directories of a program component
Every component in a graph — both dataset and program components — has a layout. Some graphs use one layout throughout; others use several layouts and repartition data when needed for processing by a greater or
COMPONENT PROPERTIES PARAMETERS: • Set various component specific configuration • Specify transform settings • Handle rejects/logs/thresholds • • • •
Apply filters Specify Keys for Sort and Partition Specify URL for transforms Parameter interpretation
COMPONENT PROPERTIES PORTS: • Assign record formats for various ports • Specify URL of record format • Interpretation settings for any environment parameters.
EDITORS EDITORS: Configuring components using various tabs involve changing settings for • • • • •
Transforms Filters Keys Record Formats Expressions
These settings are created using •
Text editors
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Various editors available on their respective item.
EDITORS: RECORD FORMAT The Record Format Editor enables you to easily create and edit record formats.
record decimal(6) cust_id; string(18) last_name; string(16) first_name; string(26) street_addr; string(2) state; string(1) newline; end;
DML DATA TYPES
EDITORS: EXPRESSION EDITOR
Functions: Displays the built-in DML functions. Fields: Displays the input record formats available for use in an expression.
Operators: Displays the built-in DML operators.
EDITORS: KEY SPECIFIER Key Specifier Editor:
Sort Sequences Sequence phonebook
index
machine
Details Digits are treated as the lowest value characters, followed by the letters of the alphabet in the order AaBbCcDd..., followed by spaces. All other characters, such as punctuation, are ignored. The order of digits is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. Is the same as phonebook ordering, except that punctuation characters are not ignored; they have lower values than all other characters. The order of punctuation characters is the machine sequence. Uses character code values in the sequence in which they are arranged in the character set of the string. For ASCII-based character sets, digits are the lowest-value characters, followed by uppercase letters, followed by lowercase letters. For EBCDIC character sets, lowercase letters are the lowest-value characters, followed by uppercase, followed by digits. For Unicode , the order is from the lowest character code value to the highest. Uses the user-defined sort order. You construct a custom
EDITORS: TRANSFORM EDITOR
out::reformat(in) = begin out.* :: in.*; out.score :: if (in.income > 1000) 1 else 2; end;
COMPONENTS INPUT FILE
Represents records read as input to a graph from one or more serial files or from a multifile. Location: Datasets Key Settings: • Data Location URL • Ports
OUTPUT FILE
Represents records written as output from a graph into one or more serial files or a multifile. Location: Datasets Key Settings: • Data Location URL • Ports Note: When the target of an OUTPUT FILE component is a particular file (such as /dev/null, NUL, a named pipe, or some other special file), the Co>Operating System never deletes and re-creates that file, nor does it ever truncate it.
COMPONENTS SORT
Sorts and merges records. SORT can be used to order records before you send them to a component that requires grouped or sorted records. Location: Sort Key Parameters: • key : The field to be used as Sort key • Max-core : Amount of memory to be used per partition.
Note: • Use Key Specifier editor to add/modify keys and sort order and sequences. • Sort orders are impacted by the sort sequence used. Character sets used can also have an impact on the sort order.
COMPONENTS FILTER BY EXPRESSION Filters records according to a DML expression. Location: Transform Key Settings: • select_expr: The expression defining the filter key
Note: Use Expression Editor to add/modify the DML expression
COMPONENTS REFORMAT
Changes the format of records by dropping fields, or by using DML expressions to add fields, combine fields, or transform the data in the records. Location: Transform Key Settings: • count: Number of transformed outputs- n. • transformn: The rules defining the transformation • select: The expression specifying any filters for input • reject-threshold: Defines the rule to abort the process. Note: Use Expression Editor to add/modify the DML expression for select Use Transform Editor to add/modify transform rules
TRANSFORM FUNCTIONS A transform function is a collection of rules that specifies how to produce result records from input records. • The exact behavior of a transform function depends on the component using it. • Transform functions express record reformatting logic. • Transform functions encapsulate a wide variety of computational knowledge that cleanses records, merges records, and aggregates records. • Transform functions perform their operations on the data records flowing into the component and write the resulting data records to the out flow. Example: The purpose of the transform function in the REFORMAT component is to construct data records flowing out of the component by: • Using all the fields in the record format of the data records flowing into the component creating a new field containing a title (Mr. or Ms.) using the gender field of the data records flowing into the component • Creating a new field containing a score computed by dividing the income field by 10 Transform functions are created and edited in the GDE Transform Editor.
TRANSFORM FUNCTIONS Transform functions (or transforms) drive nearly all data transformation and computation in Ab Initio graphs. Typical simple transforms can: • Extract the year from a date. •
Combine first and last names into a full name.
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Determine the amount owed in sales tax from a transaction amount.
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Validate and cleanse existing fields.
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Delete bad values or reject records containing invalid data.
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Set default values.
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Standardize field formats.
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Merge or aggregate records.
A transform function is a collection of business rules, local variables, and statements. The transform expresses the connections between the rules, variables, and statements, as well as the connections between these elements and the input and output fields.
TRANSFORM EDITOR Creating Transforms Transforms consists of • Rules • Variables • and Statements Relationships between them are created using the Transform Editor. The Transform Editor has two views: • Grid view: Rules are created by dragging and dropping fields from input flow, functions and operators. • Text view: Rules are created using the DML syntax.
TRANFORM EDITOR GRID VIEW
Transform Transform Function Function
Input Input Fields Fields
Output Output Fields Fields
TRANSFORM EDITOR Text View: Typically, you use text view of the Transform Editor to enter or edit transforms using DML. In addition, Ab Initio software supports the following text alternatives: You can enter the DML into a standalone text file, then include that file in the transform's package. You can select Embed and enter the DML code into the Value box on the Parameters tab of the component Properties dialog.
TRANSFORM FUNCTIONS Untyped transforms: out :: trans1(in) = begin out.x :: in.a; out.y :: in.b + 1; out.z :: in.c + 2; end; Typed transforms: decimal(12) out :: add_one(decimal(12) in) = begin out :: in + 4; end; record integer(4) x, y; end out :: fiddle(in1, double in2) = begin out.x :: size_of(in1); out.y :: in2 + in2; end;
TRANSFORM EDITOR Rule: A rule, or business rule, is an instruction in a transform function that directs the construction of one field in an output record. Rules can express everything from simple reformatting logic for field values to complex computations.
Rules are created in the expression editor triggered by right clicking the rule line. Rules can utilize functions and operators to define a specific logic.
TRANSFORM EDITOR Prioritized Rules: • Priorities can be optionally assigned to the rules for a particular output field. • They are evaluated in order of priority, starting with the assignment of lowest-numbered priority and proceeding to assignments of higher-numbered priority. • The last rule evaluated will be the one with blank priority, which places it after all others in priority. • A single output field can have multiple rules attached to it. • Prioritized rules are always evaluated in the ascending order of priority. In Text View: out :: average_part_cost(in) = begin out :1: if (in.num_parts > 0) in.total_cost / in.num_parts; out :2: 0; end;
TRANSFORM FUNCTIONS Local Variable: A local variable is a variable declared within a transform function. You can use local variables to simplify the structure of rules or to hold values used by multiple rules.
• To declare (or modify) local variables, use the Variables Editor. • To initialize local variables, drag-and-drop the variable from the Variables tab to the Output pane Alternatively, enter the equivalent DML code in the text view of the Transform Editor. For example: out::rollup(in)= begin let string(7) myvar="a"; let decimal(2) mydec=2.2; end;
Statements: A statement can assign a value to a local variable, a global variable, or an output field; define processing logic; or control the number of iterations of another statement.
COMPONENTS INPUT TABLE
unloads records from a database into a graph, allowing you to specify as the source either a database table or an SQL statement that selects records from one or more tables. Location: Database / Datasets Key Settings: • Config File: Location of the file defining key parameters to access the database. • Source: Choose to use a table or a SQL statement.
Note: Database settings and other pre-requistes needs to be completed to create the config file.
COMPONENTS JOIN
JOIN reads data from two or more input ports, combines records with matching keys according to the transform you specify, and sends the transformed records to the output port. Additional ports allow you to collect rejected and unused records. JOIN can have as many as 20 input ports. Location: Transform Key Settings: • Count: An integer from 2 to 20 specifying the total number of inputs (in ports) to join. • sorted-input: specifies the input data sorts. • Key: Name(s) of the field(s) in the input records that must have matching values for JOIN to call the transform function. • Transform: Transform function specifying
COMPONENTS Key Settings (continued): • Join-type: specifies the join method from inner-join,OuterJoin and Explicit. • Record-requiredn: dependent setting of join-type. • Dedupn: removes duplicate records on the specified port. • Selectn: Acts as a component level filter for the port. • Override-keyn: Alternative name(s) for the key field(s) for a particular inn port. • Driving: specifies the port that drives the join
COMPONENTS JOIN with DB
JOIN WITH DB joins records from the flow or flows connected to its in port with records read directly from a database, and outputs new records containing data based on, or calculated from, the joined records. Location: Database Key Settings: • DBConfigfile: A database configuration file. Specifies the database to connect to • select_sql: The SELECT statement to perform for each input record.
SPECIAL TRANSFORMS AGGREGATE
AGGREGATE generates records that summarize groups of records. ROLLUP is the newer version of the AGGREGATE component. ROLLUP offers better control over record selection, grouping and aggregation.
VECTORS A vector is an array of elements, indexed from 0. An element can be a single field or an entire record. Vectors are often used to provide a logical grouping of information. An array is a collection of elements that are logically grouped for ease of access. Each element has an index by which the element can be referenced(read or written). Example: char myarray[10] = [a, b, c, d, e, f, g, h, i, j] ;
Above is an example of an array with 10 elements of type char. The elements of this is addressed as myarray[0] The above statement will return the first element ‘a’. Indices are addressed starting from 0 to n-1 where n is declared no. of array elements
SPECIAL COMPONENTS NORMALIZE
NORMALIZE generates multiple output records from each of its input records. You can directly specify the number of output records for each input record, or the number of output records can depend on some calculation. Location : Transform Key Settings: • Transform: Either the name of the file containing the types and transform functions, or a transform string.
SPECIAL COMPONENTS DENORMALIZE SORTED
DENORMALIZE SORTED consolidates groups of related records by key into a single output record with a vector field for each group, and optionally computes summary fields in the output record for each group. Location : Transform Key Settings: • Key: Specifies the name(s) of the key field(s) the component uses to define groups of records. • Transform: Specifies either the name of the file containing the transform function, or a transform string.
PHASES AND PARALLELISM Parallelism and multifiles • Graphs can be scaled to accommodate any amount of data by introducing parallelism — doing more than one thing at the same time — into it. Data parallelism, in particular, separates the data flowing through the graph into as many divisions — called partitions. Partitions can be sent to as many processors as needed to produce the result in the desired length of time. • Ab Initio multifiles stores partitioned data wherever convenient — on different disks or on different computers in various locations, and so on — and yet manage all the partitions as a single entity.
Phases and checkpoints • Resources can be regulated by dividing a graph into stages — called phases — each of which must complete before the next begins. • Checkpoint are used at the end of any phase to guard against loss in case of failure. If a problem occurs, you can return the state of the graph to the last successfully completed checkpoint and then rerun it without having to start over from the beginning. • You set phases and checkpoints graphically in the GDE.
PARALLELISM
The power of Ab Initio software to process large quantities of data is based on its use of parallelism — doing more than one thing at the same time. The Co>Operating System uses three types of parallelism: • Component parallelism • Pipeline parallelism • Data parallelism
COMPONENT PARALLELISM Component parallelism occurs when program components execute simultaneously on different branches of a graph.
In the graph above, the CUSTOMERS and TRANSACTIONS datasets are unloaded, sorts them and merges them into a dataset named MERGED INFORMATION. Component parallelism scales to the number of branches of a graph — the more branches a graph has, the greater the component parallelism. If a graph has only one branch, component parallelism cannot occur.
PIPELINE PARALLELISM Pipeline parallelism occurs when several connected program components on the same branch of a graph execute simultaneously.
Both SCORE and SELECT read records as they become available and write each record immediately after processing it. After SCORE finishes scoring the first CUSTOMER record and sends it to SELECT, SELECT determines the destination of the record and sends it on. At the same time, SCORE reads the second CUSTOMER record. The two processing stages of the graph run concurrently — this is pipeline parallelism.
DATA PARALLELISM Data parallelism occurs when a graph separates data into multiple divisions, allowing multiple copies of program components to operate on the data in all the divisions simultaneously.
The divisions of the data and the copies of the program components that create data parallelism are called partitions, and a component partitioned in this way is called a parallel component. If each partition of a parallel program component runs on a separate processor, the increase in the speed of processing is almost directly proportional to the number of partitions.
PARTITIONS The divisions of the data and the copies of the program components that create data parallelism are called partitions, and a component partitioned in this way is called a parallel component. If each partition of a parallel program component runs on a separate processor, the increase in the speed of processing is almost directly proportional to the number of partitions. • FLOW PARTITIONS When you divide a component into partitions, you divide the flows that connect to it as well. These divisions are called flow partitions.
• PORT PARTITIONS The port to which a partitioned flow connects is partitioned as well, with the same number of port partitions as the flow connected to it. • DEPTH OF PARALLELISM The number of partitions of a component, flow, port, graph, or section of a graph determines its depth of parallelism.
PARTITIONS
PARALLEL FILES Sometimes you will want to store partitioned data in its partitioned state in a parallel file for further parallel processing. If you locate the partitions of the parallel file on different disks, the parallel components in a graph can all read from the file at the same time, rather than being limited by all having to take turns reading from the same disk. These parallel files are called multifiles.
MULTIFILE SYSTEM Multifiles are parallel files composed of individual files, which may be located on separate disks or systems. These individual files are the partitions of the multifile. Understanding the concept of multifiles is essential when you are developing parallel applications that use files, because the parallelization of data drives the parallelization of the application. Data parallelism makes it possible for Ab Initio software to process large amounts of data very quickly. In order to take full advantage of the power of data parallelism, you need to store data in its parallel state. In this state, the partitions of the data are typically located on different disks on various machines. An Ab Initio multifile is a parallel file that allows you to manage all the partitions of the data, no matter where they are located, as a single entity. Multifiles are organized by using a Multifile System, which has a directory tree structure that allows you to work with multifiles and the directory structures that contain them in the same way you would work with serial files. Using an Ab Initio multifile system, you can apply familiar file management operations to all partitions of a multifile from a central point of administration — no matter how diverse the machines on which they are located. You do this by referencing the control partition of the multifile with a single Ab Initio URL.
MULTIFILE SYSTEM Multifile • An Ab Initio multifile organizes all partitions of a multifile into one single virtual file that you can reference as one entity. • An Ab Initio multifile can only exist in the context of a multifile system. • Multifiles are created by creating a multifile system, and then either outputting parallel data to it with an Ab Initio graph, or using the m_touch command to create an empty multifile in the multifile system. Ad Hoc Multifiles • A parallel dataset with partitions that are an arbitrary set of serial files containing similar data. • Created explicitly by listing a set of serial files as partitions, or by using a shell expression that expands at runtime to a list of serial files. • The serial files listed can be anything from a serial dataset divided into multiple serial files to any set of serial files containing similar data.
MULTIFILE SYSTEM - Visualize a directory tree containing subdirectories and files.
- Now imagine 3 identical copies of the same tree located on several disks, and number them 0 to 2. These are the data partitions of the multifile system. - Then add one more copy of the tree to serve as the control partition.
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This Multifile system will be referenced on GDE using Ab Initio URLs.
mfile://pluto.us.com/usr/ed/mfs3
MULTIFILE SYSTEM Creating the Multifile system MFS m_mkfs //pluto.us.com/usr/ed/mfs3 \ //pear.us.com/p/mfs3-0 \ //pear.us.com/q/mfs3-1 \ //plum.us.com/D:/mfs3-2
Multidirectory m_mkdir //pluto.us.com/usr/ed/mfs3/cust
Multifile m_touch //pluto.us.com/usr/ed/mfs3/cust/t.out \
ASSIGNMENT Creating a Multidirectory • Open the command console. • Enter the following command m_mkdir c:\data\mfs\mfs2way\employee
LAYOUTS A layout of a component specifies : • The locations of files: A URL specifying the location of file. • The number and locations of the partitions of multifiles: A URL that specifies the location of the control partition of a multifile. Every component in a graph — both dataset and program components — has a layout. Some graphs use one layout throughout; others use several layouts. The layouts you choose can be critical to the success or failure of a graph. For a layout to be effective, it must fulfill the following requirements: • The Co>Operating System must be installed on the computers specified by the layout. • The run host must be able to connect to the computers specified by the layout. • The working directories in the layout must exist • The permissions in the directories of the layout must allow the graph to write files there. • The layout must allow enough space for the files the graph needs to write there. During execution, a graph writes various files in the layouts of some or all of the components in it.
FLOWS
FLOWS Flows indicate the type of data transfer between the components connected.
FLOWS Straight Flow: A straight flow connects components with the same depth of parallelism, including serial components, to each other. If the components are serial, the flow is serial. If the components are parallel, the flow has the same depth of parallelism as the components.
FLOWS Fan Out flow: A fan-out flow connects a component with a lesser number of partitions to one with a greater number of partitions — in other words, it follows a one-to-many pattern. The component with the greater depth of parallelism determines the depth of parallelism of a fan-out flow.
NOTE: You can only use a fan-out flow when the result of dividing the greater number of partitions by the lesser number of partitions is an integer. If this is not the case, you must use an all-to-all flow.
FLOW Fan In flow: A fan-in flow connects a component with a greater depth of parallelism to one with a lesser depth — in other words, it follows a many-to-one pattern. As with a fan-out flow, the component with the greater depth of parallelism determines the depth of parallelism of a fan-in flow.
NOTE: You can only use a fan-out flow when the result of dividing the greater number of partitions by the lesser number of partitions is an integer. If this is not the case, you must use an all-to-all flow.
FLOW All to All flow: An all-to-all flow connects components with the same or different degrees of parallelism in such a way that each output port partition of one component is connected to each input port partition of the other component.
NOTE: You can only use a fan-out flow when the result of dividing the greater number of partitions by the lesser number of partitions is an integer. If this is not the case, you must use an all-to-all flow.
SANDBOX A sandbox is a special directory (folder) containing a certain minimum number of specific subdirectories for holding Ab Initio graphs and related files. These subdirectories have standard names that indicate their function. The sandbox directory itself can have any name; its properties are recorded in various special and hidden files that lie at its top.
SANDBOX Parts of a graph • Data files (.dat) •
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The Transactions input dataset and the Transaction Data output dataset. If these are multifiles, the actual datasets will occupy multiple files. Record formats (.dml) • There are two separate record formats in the graph, one for the input file, the other for the output. These record formats could be embedded in the Input File and Output File components themselves. Transforms (.xfr) • The transform function can be embedded in the component, but (as with the record formats) Graph file (.mp) • The graph itself is stored complete as an .mp file. Deployed script (.ksh) • If deployed as a script, the graph will also exist as a .ksh file, which has to be stored somewhere.
SANDBOX Sandbox Parameters: Sandbox parameters are variables which are visible to any component in any graph which is stored in that sandbox. Here are some examples of sandbox parameters: • $PROJECT_DIR • $DML • $RUN Graphs refer to the sandbox subdirectories by using sandbox parameters.
SANDBOX Sandbox Parameters Editor
SANDBOX The default sandbox parameters in a GDE-created sandbox are these eight: PROJECT_DIR — absolute path to the sandbox directory DML — relative sandbox path to the dml subdirectory XFR — relative sandbox path to the xfr subdirectory RUN — relative sandbox path to the run subdirectory DB — relative sandbox path to the db subdirectory MP — relative sandbox path to the mp subdirectory RESOURCE — relative sandbox path to the resource subdirectory PLAN — relative sandbox path to the plan subdirectory
GRAPH PARAMETERS • • •
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Graph parameters are associated with individual graphs and are private to them. They affect the execution only of the graph for which they are defined. All the specifiable values of a graph, including each component's parameters (as well as other values such as URLs, file protections, and record formats,) comprise that graph's parameters. Graph parameters are part of the graph they are associated with and are checked in or out along with the graph. Graph Parameters are used when a graph needs to be reused or to facilitate runtime changes to certain settings of components used in the graph. These are created using Graph Parameter editor. Values to the graph parameters can be stored(pset) in a file and called during the execution of graph.
GRAPH PARAMETERS Graph Parameters Editor
PARAMETER SETTING Name: • Value: Unique identifier of the parameter. • Description: String. First character must be a letter; remaining characters can be a combination of letters, digits, and underscores. Spaces are not allowed. • Example: OUT_DATA_MFS Scope: • Value: Local or Formal. • Description: • Local: parameter receives its value from the Value column. • Formal: parameter receives its value at runtime from the command line. When run from GDE, a dialog appears prompting input values. Kind: • Sandbox • Value: Unspecified or Keyword. • Description: • Unspecified: parameter values are directly assigned on command line. • Keyword: The value for a keyword parameter is identified by a keyword preceding it. The keyword is the name of the parameter. • Graph • Value: Positional, Keyword or Environment. • Description: • Positional: The value for a positional parameter is identified by its position on the command line. • Keyword: same as Sandbox setting. • Environment: parameter receives its value from the environment.
PARAMETER SETTING Type: • Value: Common Project, Dependent, Switch or String. • Description: • Common Project: to include other shared, or common, project values within the current sandbox. • Dependent: parameters whose values depend on the value of a switch parameter. • Switch: purpose of a switch parameter is to allow you to change your sandbox's context: • String: a normal string representing record formats, file paths etc..
Dependent on: • Value: Name of the switch column.
Value: • Value: The parameter's value, consistent with its type.
Interpretation: • Value: Constant, $ substitution, ${} substitution and Shell. • Description: Determines how the string value is evaluated
Required: • Value: Required. Or Optional. • Description: Specifies the value is required or optional.
Export: • Value: Checked /Unchecked • Description: Specifies if the parameter /value needs to be exported to environment
ORDER OF EVALUATION When you run a graph, parameters are evaluated in the following order: 1. The host setup script is run. 2. Common (that is, included) project (sandbox) parameters are evaluated. 3. Project (sandbox) parameters are evaluated. 4. The project-start.ksh script is run. 5. Formal parameters are evaluated. 6. Graph parameters are evaluated. 7. The graph start script is run.
GRAPH PARAMS V/S SANDBOX PARAMS •
Graph parameters are visible only to the particular graph to which they belong
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Sandbox parameters are visible to all the graphs stored in a particular sandbox
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Graph parameters are created by Edit>Parameters on the Graph window
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Sandbox parameters are automatically created (defaults) and can be edited by Project>Edit Sandbox
or by editing the .air-project-parameters file on the root directory of the sandbox • Graph parameters are set after Sandbox parameters. If a graph parameter and a sandbox parameter shares the same name, the graph parameter has a higher precedence.
PARAMETER INTERPRETATION The value of a parameter often contains references to other parameters. This attribute specifies how you want such references to be handled in this parameter. There are four possibilities: $ substitution: This specifies that if the value for a parameter contains the name of another parameter preceded by a dollar sign ($), the dollar sign and name are replaced with the value of the parameter that's referred to. In other words, $parameter is replaced by the value of parameter. $parameter is said to be "a $ reference" or "dollar-sign reference to parameter". ${} substitution: ${} substitution is similar to $ substitution, except that it additionally requires that you surround the name of the referenced parameter with curly braces — {}. If you do not use curly braces, no substitution occurs, and the dollar sign (and the name that follows it) is taken literally. You should use $ {} substitution for parameters that are likely to have values that contain $ as a character, such as names of relational database tables. constant: The GDE uses the parameter's specified value literally, as is, with no further interpretation. If the value contains any special characters, such as $, the GDE surrounds them with single quotes in the deployed shell script, so that they are protected from any further interpretation by the shell. shell: The shell specified in the Host Settings dialog for the graph, usually the Korn shell, interprets the parameter's value. Note that the value is not a full shell command; rather, it is the equivalent of the value assigned in the definition of a shell. PDL: The Parameter Definition Language is available as an interpretation method only for the :eme value of a dependent graph parameter. PDL (Parameter Definition Language) is a simple set of notations for expressing the values of parameters—in components, Graphs, and projects.
LOOKUP A lookup file is a file of data records that is small enough to fit in main memory, letting a transform function retrieve records much more quickly than it could if they were stored on disk. Lookup files associate key values with corresponding data values to index records and retrieve them. Ab Initio’s lookup components are dataset components with special features. Data in lookups are accessed using specific functions inside transforms. Indexes are used to access the data when called by lookup functions. The data is loaded into memory for quick access. A common use for a lookup file is to hold data frequently used by a transform component. For example, if the data records of a lookup file contain numeric product codes and their corresponding product names, a component can rapidly search the lookup file to translate codes to names or names to codes.
LOOKUP Guidelines: •
Unlike other dataset components, LOOKUP FILE is not connected to other components in a graph. It has no ports. However, its contents are accessible from other components in the same phase or later phases of a graph.
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LOOKUP FILE are referred in other components by calling lookup, lookup_count, or lookup_next DML functions in any transform function or expression parameter.
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The first argument to these lookup functions is the name of the LOOKUP FILE. The remaining arguments are values to be matched against the fields named by the key parameter. The lookup functions return a record that matches the key values and has the format given by the RecordFormat parameter.
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A file to be used as a LOOKUP FILE must be small enough to fit into main memory.
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Information about LOOKUP FILE components can be stored in a catalog, and thus you can share the components with other graphs.
LOOKUP COMPONENTS: • LOOKUP • LOOKUP TEMPLATE • WRITE LOOKUP •
WRITE BLOCK COMPRESSED LOOKUP
LOOKUP DML lookup functions locate records in a lookup file based on a key. The lookup can find an exact value, a regular expression (regex) that matches the lookup expression, or an interval (range) in which the lookup expression falls. Exact: A lookup file with an exact key allows for lookups that compare one value to another. The lookup expression (in the lookup function) must evaluate to a value, and can be comprised of any number of key fields. Regex: Lookups can be configured for pattern matching: the records of the lookup file have regular expressions in their key fields and you specify that the key is regex. Interval: The lookup expression is considered to match a lookup file record if its value matches any value in the range (i.e., interval). Another way to state this: the lookup function compares a value to a series of intervals in a lookup file to determine in which interval the value falls.
LOOKUP Interval Lookup: Intervals defined using one field in each lookup record : Interval is specified to imply that the lookup file is set up such that each key is comprised of only one field: that field contains a value that is both the upper endpoint of the previous interval as well as the lower endpoint of the current interval.
Intervals defined by two fields in each lookup record: Intervals specified with interval_top and interval_bottom to imply that each lookup file record contains two key fields, one having the bottom endpoint of the range; the other, the top.
LOOKUP Key Specifier types Keyword interval
interval_bottom
interval_top
inclusive (default) exclusive
Description Specifies that the field holds a value that is both: - The lower endpoint of the current interval inclusive - The upper endpoint of the previous interval exclusive Specifies that the field holds a value that is the lower endpoint of an interval inclusive. The interval_bottom keyword must precede the interval_top keyword. Specifies that the field holds a value that is the upper endpoint of an interval inclusive. Note that interval_top must follow the interval_bottom keyword. Modifies interval_bottom and interval_top to make them inclusive. Use only with interval_top and interval_bottom. Modifies interval_bottom and interval_top to make them exclusive. Use only with interval_top and interval_bottom.
LOOKUP •
Each record in the lookup file represents an interval, that is, a range of values. The lower and upper bounds of the range are usually given in two separate fields of the same type.
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A key field marked interval_bottom holds the lower endpoint of the interval.
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A key field marked interval_top holds the upper endpoint.
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If a field in the lookup file's key specifier is specified as interval, it must be the only key field for that lookup file. You cannot specify a multipart key as an interval lookup.
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The file contains well-formed intervals: • For each record, the value of the lower endpoint of the interval must be less than or equal to the value of the upper endpoint of the intervals. • The intervals must not overlap. • The intervals must be sorted into ascending order.
LOOKUP Ways to use Lookup: Static: LOOKUP FILE component. The lookup file is read into memory when its graph phase starts and stays in memory until the phase ends. You set up this kind of lookup by placing a LOOKUP FILE component in the graph. Unlike other dataset components, the LOOKUP FILE component has no ports; it does not need to be connected to other components. However, its contents are accessible from other components in the same or later phases of the graph. A LOOKUP FILE component lookup has the advantage of being simple to use: you add a LOOKUP FILE component to a graph, set its properties, and then call a lookup function.
LOOKUP Dynamic: The lookup file (or just its index if the file is block-compressed) is read into memory only when you call a loading function from within a transform; you later unload the lookup file by calling a lookup_unload function. A dynamically loaded lookup provides these advantages: • You can specify the lookup file name at runtime rather than when you create the graph • You can avoid having multiple lookup files or indexes take up a lot of memory — this is especially relevant in a graph that uses many lookup files. • A graph need load only the relevant partition of a lookup file rather than the entire file — this saves memory in a graph where a component and lookup file are identically partitioned
LOOKUP Catalogued Lookup: Information about lookup files can be stored in a catalog, so that you can share the lookup files among multiple graphs by simply sharing the catalog. A catalog is a file that stores a list of lookup files on a particular run host. To make a catalog available to a graph, you use the Shared Catalog Path on the Catalog tab of the Run Settings dialog to indicate• where find the shared Ignoreto shared catalog, use lookup files only (default) — catalog. •
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Ignores the shared catalog Use shared catalog and lookup files — Accesses the files in the shared catalog along with lookup files in the graph. Add lookup files to shared catalog permanently — Adds lookup files in the graph to the shared catalog, then uses the shared catalog. Create new shared catalog from lookup files — Removes all lookup files from the shared catalog and replaces them with the lookup
LOOKUP Uncompressed lookup files: • Any file can serve as an uncompressed lookup file if the data is not compressed and has a field defined as a key. These files can also be created using the WRITE LOOKUP component. • The component writes two files: • a file containing the lookup data and • an index file that references the data file.
Block-compressed lookup files: • Lookup files are written in compressed indexed blocks. These kind of files are created using the WRITE BLOCK COMPRESSED LOOKUP component. • The component writes two files: • A data file containing the blocks of compressed data • An index file that contains indexes to the blocks
When you load a block-compressed lookup file you are actually loading its index file. The compressed data remains on disk.
LOOKUP Lookup files can be either serial or partitioned (multifiles). Serial: • When a serial lookup file is accessed in a component, the Co>Operating System loads the entire file into memory. In most cases the file is memory-mapped: every component in your graph that uses that lookup file (and is on the same machine) shares a copy of that file. If the component is running in parallel, all partitions on the same machine also share a single copy of the lookup file. • lookup, lookup_count, lookup_match, lookup_next, and lookup_nth are used with serial files Partitioned: • Partitioning a lookup file is particularly useful when a multifile system is partitioned across several machines. The depth of the lookup file (the number of ways it is partitioned) must match the layout depth of the component accessing it. • lookup_local, lookup_count_local, lookup_match_local, lookup_next_local and lookup_nth_local are used with partitioned lookup files
LOOKUP Lookup Functions: lookup[_local] record lookup[_local] (string file_label, [ expression [ , expression ... ]])
Returns the first matching data record, if any, from a [partition of a] lookup file. lookup_count[_local] unsigned long lookup_count[_local] (string file_label, [expression [ ,expression ..]])
Returns the number of matching data records in a [partition of a] lookup file. lookup_match[_local] unsigned long lookup_match[_local] (string file_label, [expression [ ,expression .. ]])
Looks up a specified match in a [partition of a] lookup file.
LOOKUP lookup_next[_local] record lookup_next[_local] (string file_label )
Returns the next successive matching record, if any, from a [partition of a] lookup file after a successful call to lookup or lookup_count. lookup_nth[_local] record lookup_nth[_local] (string file_label, unsigned integer record_num )
Returns a specific record from a [partition of a] lookup file.
LOOKUP Dynamically loaded lookup: Unlike the normal lookup process, dynamically loaded lookups load the dataset only when it is called by a lookup_load function in any transformation on the graph. This provides an opportunity to dynamically specify which file to use as a lookup. Dynamically loaded lookups are used in a specific sequence: • Prepare a LOOKUP_TEMPLATE component • Use lookup_load to load the dataset and its index lookup(lookup_id, "MyLookupTemplate", in.expression)
• Call the standard lookup function within a transform • Unload the lookup using lookup_unload function
LOOKUP Tips: • A lookup file works best if it has a fixed-length record format because this creates a smaller index and thus faster lookups. • When creating a lookup file from source data, drop any fields that are not keys or lookup results. • A lookup file represented by a LOOKUP FILE component must fit into memory. If a file is too large to fit into memory, use INPUT FILE followed by MATCH SORTED or JOIN instead. • If the lookup file is large, partition the file on its key the same way as the input data is partitioned. Then use the functions lookup_local, lookup_count_local, or lookup_next_local. For more information, see "Partitioned lookup files".
