OpenEdge Data Management: DataServer for Microsoft SQL Server

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Chapter 2: Initial Programming Considerations Transactions With DataServer operations, a MS SQL Server data source handles its own transaction roll back and recovery operations. However, the OpenEdge transaction scoping rules apply: a transaction ends when the code exits the outermost block that performs an update. With the DataServer, ABL performs as follows: • Sends a COMMIT to the data source, when a transaction that updates a MS SQL Server data source ends successfully.c • Sends a ROLLBACK to the data source if you interrupt the transaction. See OpenEdge Getting Started: ABL Essentials for details on how ABL handles transactions and error conditions. Transaction scoping and buffer management The DataServer and an OpenEdge database hold locks differently at transaction boundaries. The OpenEdge database will hold a lock past the transaction boundary where the DataServer will not. This causes different behavior in the use of buffers. Consider the following example: DEFINE BUFFER st_buf1 FOR state. DEFINE BUFFER st_buf2 FOR state. DO TRANSACTION: /* Transaction 1 */ FIND st_buf1 WHERE st_buf1.state EQ "NH" EXCLUSIVE-LOCK. DISPLAY st_buf1.state-name. /* state-name = "New Hampshire" */ END. /* During this pause, state-name is changed from "New Hampshire" to "Granite State" by an external user */ PAUSE MESSAGE " state.state-name ". DO TRANSACTION: /* Transaction 2 */ FIND st_buf2 WHERE st_buf2.state EQ "NH" EXCLUSIVE-LOCK. DISPLAY st_buf1.state-name st_buf2.state-name. END. Executing the above code against an OpenEdge database will downgrade the EXCLUSIVE-LOCK in Transaction 1 to a SHARE-LOCK. This occurs at the end of Transaction 1 and remains in effect at the time of the PAUSE statement and prior to the start of Transaction 2. This SHARE-LOCK prevents another user from modifying the state-name value between the transactions. As an optimization, when Transaction 2 is executed, the client does not refresh the st_buf1 buffer since the SHARE-LOCK prevented its contents from becoming stale between transactions. Also, since st_buf2 will have the same data integrity as st_buf1, they share the same buffer content. Executing the above code against the DataServer will have different results because the DataServer does not retain any lock conditions beyond the scope of the transaction boundary. The DataServer will release the EXCLUSIVE-LOCK on the record at the END statement of Transaction 1. This leaves the record exposed to modification by another client during the PAUSE statement. If another client modifies the state-name value to “Granite State” during the PAUSE, Transaction 2 will read the updated value during the FIND statement. However, because of OpenEdge buffering rules and record scoping, neither buffer is refreshed with the updated value and the DISPLAY statement displays “New Hampshire New Hampshire.” 100 OpenEdge Data Management: DataServer for Microsoft SQL Server
To avoid this type of problem, the following workarounds are available: Transactions • Change the lock status in Transaction 1 to NO-LOCK if an EXCLUSIVE-LOCK is not required. The lock upgrade in Transaction 2 will force the buffer to be updated in this transaction. • If the lock can not be changed in Transaction 1, release the first buffer before the start of Transaction 2 with the statement “RELEASE st_buf1.” The RELEASE statement will force a refresh of the data when the FIND in Transaction 2 executes. OpenEdge Data Management: DataServer for Microsoft SQL Server 101
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® ® PROGRESS® OPENEDGE® OpenEdg
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Contents Preface . . . . . . . . .
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Contents Data output and retrieval
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Contents Migrating an OpenEdge data
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Tables Contents Table 1: DataServer
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Examples Contents Example 1: Passin
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Preface This Preface contains the f
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Chapter 5, “Configuring the DataS
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Before you begin Preface Before att
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In this example, STREAM stream, UNL
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After displaying a message, OpenEdg
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Preface Software Foundation (http:/
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Preface use, copy, modify, and dist
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Preface DISCLAIMS ALL WARRANTIES WI
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Preface INCLUDING ALL IMPLIED WARRA
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Preface WARRANTIES OF MERCHANTABILI
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Preface conditions for packages lik
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Introduction OpenEdge Data Manageme
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DataServer components DataServer co
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DataServer for MS SQL Server logic
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Figure 3 illustrates the schema-loa
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DataServer utilities DataServer uti
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DataServer configurations DataServe
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The remote DataServer configuration
Page 49 and 50: DataServer configurations Configuri
Page 51 and 52: Software requirements Software requ
Page 53 and 54: Guidelines for using the DataServer
Page 55 and 56: Initial Programming Considerations
Page 57 and 58: Database design issues Database des
Page 59 and 60: MS SQL Server DataServer data sourc
Page 61 and 62: Client code page Database design is
Page 63 and 64: Support for Unicode Database design
Page 65 and 66: Indexes and sorting Database design
Page 67 and 68: Database design issues source’s c
Page 69 and 70: Triggers Database design issues Tri
Page 71 and 72: Data types Data types MS SQL Server
Page 73 and 74: Table 9: MS SQL Server data type eq
Page 75 and 76: Processing activities that require
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Page 79 and 80: Performing data type conversions Da
Page 81 and 82: Enabling Datetime data types using
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Page 85 and 86: Default and Special Datetime Defaul
Page 87 and 88: ABL-to-MS SQL Server data type mapp
Page 89 and 90: Unknown value (?) Data types The Da
Page 91 and 92: Record creation Suppose that you ha
Page 93 and 94: Data source record locking Data sou
Page 95 and 96: Handling lock timeouts Data source
Page 97 and 98: Locking impact on queries Data sour
Page 99: Data source record locking When thi
Page 103 and 104: Error handling If you use NO-ERROR
Page 105 and 106: Cursors Cursors A cursor is like a
Page 107 and 108: Cursors your specifications. Adjust
Page 109 and 110: • Block cursors are directly link
Page 111 and 112: FIND customer WHERE ROWID(customer)
Page 113 and 114: For example, the following statemen
Page 115 and 116: find.p /* This code accesses an Ope
Page 117 and 118: ABL issues Table 19 summarizes ABL
Page 119 and 120: RDBMS Stored Procedure Details Open
Page 121 and 122: RDBMS stored procedure basics RDBMS
Page 123 and 124: RDBMS stored procedure basics When
Page 125 and 126: Run Stored-Procedure details •
Page 127 and 128: Run Stored-Procedure details An exp
Page 129 and 130: Run Stored-Proc statement execution
Page 131 and 132: Run Stored-Procedure details Also n
Page 133 and 134: Loading results into a temp-table T
Page 135 and 136: Retrieving return codes Interfacing
Page 137 and 138: Interfacing with RDBMS stored proce
Page 141 and 142: Loading result sets into temp-table
Page 143 and 144: Employing additional enhancements I
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Handling errors Handling errors The
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ROWID Support This section presents
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ROWID Support The RUN STORED-PROC c
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ROWID Support If the table uses com
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Additional Features to Enhance Data
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Connection pooling Connection pooli
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DataServer connection management Co
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Firehose exclusions Connection pool
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Cursor downgrades Connection poolin
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Query tuning Query tuning How you s
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LOOKAHEAD NO-LOOKAHEAD SEPARATE-CON
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Query tuning Table 24: Query-tuning
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Join by SQLDB Join by SQLDB For que
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Table 25 describes how these contro
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Modifying the run-time schema check
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Configuring the DataServer Configur
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DataServer components Table 26: Ins
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Configuring a local DataServer Conf
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Configuring a remote DataServer 4.
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5162 Configuring a remote DataServe
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The ubroker.properties file Configu
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Configuring a remote DataServer Tab
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Configuring a remote DataServer The
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Creating a schema holder Creating a
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Creating a schema holder configurat
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Creating a schema holder 3. In the
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Creating a schema holder 10. Choose
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Typical configuration for a remote
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Typical configuration for a remote
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Connecting the DataServer You can s
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Starting a remote DataServer Starti
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Starting a remote DataServer If you
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Starting a remote DataServer Starti
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Connection guidelines Connection gu
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Connecting a schema holder at start
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Single-User Mode (-1) Read-Only (-R
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Using a remote DataServer configura
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Value pairs within the connect stri
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Connecting a schema holder Table 31
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qt_separate_connection qt_no_separa
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Connecting a schema holder Table 33
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Connecting a schema holder 1. Each
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Table 38 lists the DataServer log e
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Logging levels You can choose one o
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Enabling ABL to SQL Correlation in
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Connecting a schema holder Example
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Connection failures and OpenEdge re
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Connection failures and OpenEdge re
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Using the $UNIQUE_DSLOG environment
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The DataServer Tutorial OpenEdge Da
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Demonstration databases for DataSer
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Preparing to create demonstration d
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DataServer utilities When you acces
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Prime to ROWID identification ROWID
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Prime to ROWID identification inacc
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Creating a schema holder • Choose
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Creating a schema holder You can se
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Updating a schema holder Updating a
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Verifying a schema holder Verifying
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Verifying a schema holder 2. Type p
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Changing connection information in
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Deleting a schema holder Deleting a
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Managing server attributes See the
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Managing server attributes Defining
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Managing server attributes If the p
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Managing server attributes 6. The P
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Defining a default constraint defin
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Managing server attributes 5. Click
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Managing server attributes • Resu
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Migrating an OpenEdge database to M
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Delta df to MS SQL Server Increment
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Modifying field-level information Y
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Defining the ROWID Modifying a sche
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Adding extended ABL support Adding
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Adding extended ABL support 4. Chan
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Adding extended ABL support 3. Drop
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Troubleshooting This chapter descri
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ODBC options ODBC options The DataS
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ODBC options Table 56: DataServer o
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Using MS SQL Server and DataServer
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Large rows—the PRGRS_MINBUF optio
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ODBC options Wait time for asynchro
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Using the block cursor switches ODB
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Migration Issues This appendix disc
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Modifying your application Note the
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Sample code for the db.owner.Custom
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Server Related Command Line Utiliti
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OpenEdge Management or OpenEdge Exp
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Syntax Parameters service-name PROB
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Other command line utilities for th
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Data Type Details C This appendix s
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nvarchar 8 SQL_NVARCHAR CHARACTER t
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Using qt_debug to Analyze Performan
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Using qt_debug to analyze performan
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Index Numbers 4GLTrans log entry ty
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display format 309 overflow checkin
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INPUT-OUTPUT option retrieving para
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DataServer (-Dsrv) startup paramete
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221, 242, 359 Schema defined 40 loa
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OpenEdge Data Management: DataServer for Microsoft SQL Server

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