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Overview
Comment:Re-factored memory allocation failure handling in the sqlite3LimitWhere() function based on failures in the mallocJ.test script. (CVS 5791)
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SHA1: 43507bbefbf79e8db8fe31319ad621d48247983f
User & Date: shane 2008-10-10 13:35:58.000
Context
2008-10-10
14:27
Simplify the parser reduction code for the LIMIT clause on an UPDATE or DELETE. (CVS 5792) (check-in: 3de179630e user: drh tags: trunk)
13:35
Re-factored memory allocation failure handling in the sqlite3LimitWhere() function based on failures in the mallocJ.test script. (CVS 5791) (check-in: 43507bbefb user: shane tags: trunk)
13:34
Added mallocJ.test to test allocation failure handling of the new LIMIT/OFFSET support for UPDATE/DELETE. (CVS 5790) (check-in: 5375b348b1 user: shane tags: trunk)
Changes
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Changes to src/delete.c.
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**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** in order to generate code for DELETE FROM statements.
**
** $Id: delete.c,v 1.179 2008/10/10 04:34:16 shane Exp $
** $Id: delete.c,v 1.180 2008/10/10 13:35:58 shane Exp $
*/
#include "sqliteInt.h"

/*
** Look up every table that is named in pSrc.  If any table is not found,
** add an error message to pParse->zErrMsg and return NULL.  If all tables
** are found, return a pointer to the last table.
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  if (!pLimit && !pOffset) return pWhere;

  /* Generate a select expression tree to enforce the limit/offset 
  ** term for the DELETE or UPDATE statement.  For example:
  **   DELETE FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
  ** becomes:
  **   DELETE FROM table_a WHERE rowid IN ( 
  **     DELETE rowid FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
  **     SELECT rowid FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
  **   );
  */

  pSelectRowid = sqlite3Expr(pParse->db, TK_ROW, 0, 0, 0);
  if( pSelectRowid == 0 ) goto limit_where_cleanup;
  if( pSelectRowid == 0 ) return 0;
  pEList = sqlite3ExprListAppend(pParse, 0, pSelectRowid, 0);
  if( pEList == 0 ) goto limit_where_cleanup;
  if( pEList == 0 ) return 0;

  /* duplicate the FROM clause as it is needed by both the DELETE/UPDATE tree
  ** and the DELETE tree. */
  ** and the SELECT subtree. */
  pSelectSrc = sqlite3SrcListDup(pParse->db, pSrc);
  if( pSelectSrc == 0 ) goto limit_where_cleanup;
  /* generate the DELETE expression tree. */
  if( pSelectSrc == 0 ) {
    sqlite3ExprListDelete(pParse->db, pEList);
    return 0;
  }

  /* generate the SELECT expression tree. */
  pSelect = sqlite3SelectNew(pParse,pEList,pSelectSrc,pWhere,0,0,pOrderBy,0,pLimit,pOffset);
  if( pSelect == 0 ) goto limit_where_cleanup;
  /* generate the WHERE rowid IN ( select ) expression */
  if( pSelect == 0 ) return 0;

  pWhereRowid = sqlite3Expr(pParse->db, TK_ROW, 0, 0, 0);
  if( pWhereRowid == 0 ) goto limit_where_cleanup;
  pInClause = sqlite3PExpr(pParse, TK_IN, pWhereRowid, 0, 0);
  if( pInClause == 0 ) goto limit_where_cleanup;

  pInClause->pSelect = pSelect;
  sqlite3ExprSetHeight(pParse, pInClause);
  return pInClause;

limit_where_cleanup:
  /* something went wrong. clean up anything allocated. */
  sqlite3SrcListDelete(pParse->db, pSelectSrc);
  sqlite3ExprListDelete(pParse->db, pEList);
  sqlite3ExprDelete(pParse->db, pSelectRowid);
limit_where_cleanup:
  sqlite3SelectDelete(pParse->db, pSelect);
  sqlite3ExprDelete(pParse->db, pInClause);
  sqlite3ExprDelete(pParse->db, pWhereRowid);
  return 0;
}
#endif /* defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY) */

/*
** Generate code for a DELETE FROM statement.
**
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