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Re: Allow arbitrary levels of analyze/rewriting

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Fernando Nasser <fnasser(at)redhat(dot)com>
Cc: pgsql-patches(at)postgresql(dot)org
Subject: Re: Allow arbitrary levels of analyze/rewriting
Date: 2002-02-25 04:22:03
Message-ID: 200202250422.g1P4M3K07112@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-patches
Patch applied.  Thanks.

---------------------------------------------------------------------------


Fernando Nasser wrote:
> Hi,
> 
> This patch will allow arbitrary levels of analyze / rewriting
> by making the static variables extra_before and extra_after 
> automatic so we can use recursion. 
> 
> It gets much easier to generate extra commands now, and one can rest
> assured that the extra commands will be properly analyzed/rewritten.
> 
> 
> Without this patch, if a command produced by transformation tries to
> use these static lists their first contents would be lost with
> unpredictable results.  I know I could fix this by just using nconc()
> instead of assignments, but the resulting order of the commands would
> not be exactly what one could expect. 
> 
> -- 
> Fernando Nasser
> Red Hat Canada Ltd.                     E-Mail:  fnasser(at)redhat(dot)com
> 2323 Yonge Street, Suite #300
> Toronto, Ontario   M4P 2C9

> Index: src/backend/parser/analyze.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql/src/backend/parser/analyze.c,v
> retrieving revision 1.213
> diff -c -p -r1.213 analyze.c
> *** src/backend/parser/analyze.c	2002/01/03 23:21:31	1.213
> --- src/backend/parser/analyze.c	2002/02/12 15:35:58
> *************** typedef struct
> *** 64,80 ****
>   } CreateStmtContext;
>   
>   
> ! static Query *transformStmt(ParseState *pstate, Node *stmt);
>   static Query *transformDeleteStmt(ParseState *pstate, DeleteStmt *stmt);
> ! static Query *transformInsertStmt(ParseState *pstate, InsertStmt *stmt);
>   static Query *transformIndexStmt(ParseState *pstate, IndexStmt *stmt);
> ! static Query *transformRuleStmt(ParseState *query, RuleStmt *stmt);
>   static Query *transformSelectStmt(ParseState *pstate, SelectStmt *stmt);
>   static Query *transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt);
>   static Node *transformSetOperationTree(ParseState *pstate, SelectStmt *stmt);
>   static Query *transformUpdateStmt(ParseState *pstate, UpdateStmt *stmt);
> ! static Query *transformCreateStmt(ParseState *pstate, CreateStmt *stmt);
> ! static Query *transformAlterTableStmt(ParseState *pstate, AlterTableStmt *stmt);
>   static void transformColumnDefinition(ParseState *pstate,
>   						  CreateStmtContext *cxt,
>   						  ColumnDef *column);
> --- 64,85 ----
>   } CreateStmtContext;
>   
>   
> ! static Query *transformStmt(ParseState *pstate, Node *stmt,
> ! 						List **extras_before, List **extras_after);
>   static Query *transformDeleteStmt(ParseState *pstate, DeleteStmt *stmt);
> ! static Query *transformInsertStmt(ParseState *pstate, InsertStmt *stmt,
> ! 						List **extras_before, List **extras_after);
>   static Query *transformIndexStmt(ParseState *pstate, IndexStmt *stmt);
> ! static Query *transformRuleStmt(ParseState *query, RuleStmt *stmt,
> ! 						List **extras_before, List **extras_after);
>   static Query *transformSelectStmt(ParseState *pstate, SelectStmt *stmt);
>   static Query *transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt);
>   static Node *transformSetOperationTree(ParseState *pstate, SelectStmt *stmt);
>   static Query *transformUpdateStmt(ParseState *pstate, UpdateStmt *stmt);
> ! static Query *transformCreateStmt(ParseState *pstate, CreateStmt *stmt,
> ! 						List **extras_before, List **extras_after);
> ! static Query *transformAlterTableStmt(ParseState *pstate, AlterTableStmt *stmt,
> ! 						List **extras_before, List **extras_after);
>   static void transformColumnDefinition(ParseState *pstate,
>   						  CreateStmtContext *cxt,
>   						  ColumnDef *column);
> *************** static Oid	transformFkeyGetColType(Creat
> *** 101,109 ****
>   static void release_pstate_resources(ParseState *pstate);
>   static FromExpr *makeFromExpr(List *fromlist, Node *quals);
>   
> - /* kluge to return extra info from transformCreateStmt() */
> - static List *extras_before;
> - static List *extras_after;
>   
>   
>   /*
> --- 106,111 ----
> *************** parse_analyze(Node *parseTree, ParseStat
> *** 121,137 ****
>   	List	   *result = NIL;
>   	ParseState *pstate = make_parsestate(parentParseState);
>   	Query	   *query;
>   
> ! 	extras_before = extras_after = NIL;
> ! 
> ! 	query = transformStmt(pstate, parseTree);
>   	release_pstate_resources(pstate);
>   
>   	while (extras_before != NIL)
>   	{
> ! 		result = lappend(result,
> ! 						 transformStmt(pstate, lfirst(extras_before)));
> ! 		release_pstate_resources(pstate);
>   		extras_before = lnext(extras_before);
>   	}
>   
> --- 123,138 ----
>   	List	   *result = NIL;
>   	ParseState *pstate = make_parsestate(parentParseState);
>   	Query	   *query;
> + 	/* Lists to return extra commands from transformation */
> + 	List *extras_before = NIL;
> + 	List *extras_after = NIL;
>   
> ! 	query = transformStmt(pstate, parseTree, &extras_before, &extras_after);
>   	release_pstate_resources(pstate);
>   
>   	while (extras_before != NIL)
>   	{
> ! 		result = nconc(result, parse_analyze(lfirst(extras_before), pstate));
>   		extras_before = lnext(extras_before);
>   	}
>   
> *************** parse_analyze(Node *parseTree, ParseStat
> *** 139,147 ****
>   
>   	while (extras_after != NIL)
>   	{
> ! 		result = lappend(result,
> ! 						 transformStmt(pstate, lfirst(extras_after)));
> ! 		release_pstate_resources(pstate);
>   		extras_after = lnext(extras_after);
>   	}
>   
> --- 140,146 ----
>   
>   	while (extras_after != NIL)
>   	{
> ! 		result = nconc(result, parse_analyze(lfirst(extras_after), pstate));
>   		extras_after = lnext(extras_after);
>   	}
>   
> *************** release_pstate_resources(ParseState *pst
> *** 164,170 ****
>    *	  transform a Parse tree into a Query tree.
>    */
>   static Query *
> ! transformStmt(ParseState *pstate, Node *parseTree)
>   {
>   	Query	   *result = NULL;
>   
> --- 163,170 ----
>    *	  transform a Parse tree into a Query tree.
>    */
>   static Query *
> ! transformStmt(ParseState *pstate, Node *parseTree,
> ! 			  List **extras_before,	List **extras_after)
>   {
>   	Query	   *result = NULL;
>   
> *************** transformStmt(ParseState *pstate, Node *
> *** 174,180 ****
>   			 * Non-optimizable statements
>   			 */
>   		case T_CreateStmt:
> ! 			result = transformCreateStmt(pstate, (CreateStmt *) parseTree);
>   			break;
>   
>   		case T_IndexStmt:
> --- 174,181 ----
>   			 * Non-optimizable statements
>   			 */
>   		case T_CreateStmt:
> ! 			result = transformCreateStmt(pstate, (CreateStmt *) parseTree,
> ! 									extras_before, extras_after);
>   			break;
>   
>   		case T_IndexStmt:
> *************** transformStmt(ParseState *pstate, Node *
> *** 182,195 ****
>   			break;
>   
>   		case T_RuleStmt:
> ! 			result = transformRuleStmt(pstate, (RuleStmt *) parseTree);
>   			break;
>   
>   		case T_ViewStmt:
>   			{
>   				ViewStmt   *n = (ViewStmt *) parseTree;
>   
> ! 				n->query = transformStmt(pstate, (Node *) n->query);
>   
>   				/*
>   				 * If a list of column names was given, run through and
> --- 183,198 ----
>   			break;
>   
>   		case T_RuleStmt:
> ! 			result = transformRuleStmt(pstate, (RuleStmt *) parseTree,
> ! 									extras_before, extras_after);
>   			break;
>   
>   		case T_ViewStmt:
>   			{
>   				ViewStmt   *n = (ViewStmt *) parseTree;
>   
> ! 				n->query = transformStmt(pstate, (Node *) n->query,
> ! 									extras_before, extras_after);
>   
>   				/*
>   				 * If a list of column names was given, run through and
> *************** transformStmt(ParseState *pstate, Node *
> *** 239,258 ****
>   
>   				result = makeNode(Query);
>   				result->commandType = CMD_UTILITY;
> ! 				n->query = transformStmt(pstate, (Node *) n->query);
>   				result->utilityStmt = (Node *) parseTree;
>   			}
>   			break;
>   
>   		case T_AlterTableStmt:
> ! 			result = transformAlterTableStmt(pstate, (AlterTableStmt *) parseTree);
>   			break;
>   
>   			/*
>   			 * Optimizable statements
>   			 */
>   		case T_InsertStmt:
> ! 			result = transformInsertStmt(pstate, (InsertStmt *) parseTree);
>   			break;
>   
>   		case T_DeleteStmt:
> --- 242,264 ----
>   
>   				result = makeNode(Query);
>   				result->commandType = CMD_UTILITY;
> ! 				n->query = transformStmt(pstate, (Node *) n->query,
> ! 								extras_before, extras_after);
>   				result->utilityStmt = (Node *) parseTree;
>   			}
>   			break;
>   
>   		case T_AlterTableStmt:
> ! 			result = transformAlterTableStmt(pstate, (AlterTableStmt *) parseTree,
> ! 										extras_before, extras_after);
>   			break;
>   
>   			/*
>   			 * Optimizable statements
>   			 */
>   		case T_InsertStmt:
> ! 			result = transformInsertStmt(pstate, (InsertStmt *) parseTree,
> ! 										extras_before, extras_after);
>   			break;
>   
>   		case T_DeleteStmt:
> *************** transformDeleteStmt(ParseState *pstate, 
> *** 337,343 ****
>    *	  transform an Insert Statement
>    */
>   static Query *
> ! transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
>   {
>   	Query	   *qry = makeNode(Query);
>   	List	   *sub_rtable;
> --- 343,350 ----
>    *	  transform an Insert Statement
>    */
>   static Query *
> ! transformInsertStmt(ParseState *pstate, InsertStmt *stmt,
> ! 					List **extras_before, List **extras_after)
>   {
>   	Query	   *qry = makeNode(Query);
>   	List	   *sub_rtable;
> *************** transformInsertStmt(ParseState *pstate, 
> *** 402,408 ****
>   		sub_pstate->p_rtable = sub_rtable;
>   		sub_pstate->p_namespace = sub_namespace;
>   
> ! 		selectQuery = transformStmt(sub_pstate, stmt->selectStmt);
>   
>   		release_pstate_resources(sub_pstate);
>   		pfree(sub_pstate);
> --- 409,420 ----
>   		sub_pstate->p_rtable = sub_rtable;
>   		sub_pstate->p_namespace = sub_namespace;
>   
> ! 		/*
> ! 		 * Note: we are not expecting that extras_before and extras_after
> ! 		 * are going to be used by the transformation of the SELECT statement.
> !  		 */
> ! 		selectQuery = transformStmt(sub_pstate, stmt->selectStmt,
> ! 								extras_before, extras_after);
>   
>   		release_pstate_resources(sub_pstate);
>   		pfree(sub_pstate);
> *************** CreateIndexName(char *table_name, char *
> *** 658,664 ****
>    *	  - thomas 1997-12-02
>    */
>   static Query *
> ! transformCreateStmt(ParseState *pstate, CreateStmt *stmt)
>   {
>   	CreateStmtContext cxt;
>   	Query	   *q;
> --- 670,677 ----
>    *	  - thomas 1997-12-02
>    */
>   static Query *
> ! transformCreateStmt(ParseState *pstate, CreateStmt *stmt,
> ! 					List **extras_before, List **extras_after)
>   {
>   	CreateStmtContext cxt;
>   	Query	   *q;
> *************** transformCreateStmt(ParseState *pstate, 
> *** 728,735 ****
>   	q->utilityStmt = (Node *) stmt;
>   	stmt->tableElts = cxt.columns;
>   	stmt->constraints = cxt.ckconstraints;
> ! 	extras_before = cxt.blist;
> ! 	extras_after = cxt.alist;
>   
>   	return q;
>   }
> --- 741,748 ----
>   	q->utilityStmt = (Node *) stmt;
>   	stmt->tableElts = cxt.columns;
>   	stmt->constraints = cxt.ckconstraints;
> ! 	*extras_before = nconc (*extras_before, cxt.blist);
> ! 	*extras_after = nconc (cxt.alist, *extras_after);
>   
>   	return q;
>   }
> *************** transformIndexStmt(ParseState *pstate, I
> *** 1668,1674 ****
>    *	  trees which is transformed into a list of query trees.
>    */
>   static Query *
> ! transformRuleStmt(ParseState *pstate, RuleStmt *stmt)
>   {
>   	Query	   *qry;
>   	RangeTblEntry *oldrte;
> --- 1681,1688 ----
>    *	  trees which is transformed into a list of query trees.
>    */
>   static Query *
> ! transformRuleStmt(ParseState *pstate, RuleStmt *stmt,
> ! 				List **extras_before, List **extras_after)
>   {
>   	Query	   *qry;
>   	RangeTblEntry *oldrte;
> *************** transformRuleStmt(ParseState *pstate, Ru
> *** 1797,1803 ****
>   			addRTEtoQuery(sub_pstate, newrte, false, true);
>   
>   			/* Transform the rule action statement */
> ! 			top_subqry = transformStmt(sub_pstate, action);
>   
>   			/*
>   			 * We cannot support utility-statement actions (eg NOTIFY)
> --- 1811,1818 ----
>   			addRTEtoQuery(sub_pstate, newrte, false, true);
>   
>   			/* Transform the rule action statement */
> ! 			top_subqry = transformStmt(sub_pstate, action,
> ! 								extras_before, extras_after);
>   
>   			/*
>   			 * We cannot support utility-statement actions (eg NOTIFY)
> *************** transformUpdateStmt(ParseState *pstate, 
> *** 2494,2500 ****
>    *	transform an Alter Table Statement
>    */
>   static Query *
> ! transformAlterTableStmt(ParseState *pstate, AlterTableStmt *stmt)
>   {
>   	CreateStmtContext cxt;
>   	Query	   *qry;
> --- 2509,2516 ----
>    *	transform an Alter Table Statement
>    */
>   static Query *
> ! transformAlterTableStmt(ParseState *pstate, AlterTableStmt *stmt,
> ! 						List **extras_before, List **extras_after)
>   {
>   	CreateStmtContext cxt;
>   	Query	   *qry;
> *************** transformAlterTableStmt(ParseState *psta
> *** 2534,2541 ****
>   			transformFKConstraints(pstate, &cxt);
>   
>   			((ColumnDef *) stmt->def)->constraints = cxt.ckconstraints;
> ! 			extras_before = cxt.blist;
> ! 			extras_after = cxt.alist;
>   			break;
>   
>   		case 'C':
> --- 2550,2557 ----
>   			transformFKConstraints(pstate, &cxt);
>   
>   			((ColumnDef *) stmt->def)->constraints = cxt.ckconstraints;
> ! 			*extras_before = nconc(*extras_before, cxt.blist);
> ! 			*extras_after = nconc(cxt.alist, *extras_after);
>   			break;
>   
>   		case 'C':
> *************** transformAlterTableStmt(ParseState *psta
> *** 2571,2578 ****
>   
>   			Assert(cxt.columns == NIL);
>   			stmt->def = (Node *) nconc(cxt.ckconstraints, cxt.fkconstraints);
> ! 			extras_before = cxt.blist;
> ! 			extras_after = cxt.alist;
>   			break;
>   
>   		default:
> --- 2587,2594 ----
>   
>   			Assert(cxt.columns == NIL);
>   			stmt->def = (Node *) nconc(cxt.ckconstraints, cxt.fkconstraints);
> ! 			*extras_before = nconc(*extras_before, cxt.blist);
> ! 			*extras_after = nconc(cxt.alist, *extras_after);
>   			break;
>   
>   		default:

> 
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-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

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