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postgresql/src/include/executor/nodeLimit.h

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Re-implement LIMIT/OFFSET as a plan node type, instead of a hack in ExecutorRun. This allows LIMIT to work in a view. Also, LIMIT in a cursor declaration will behave in a reasonable fashion, whereas before it was overridden by the FETCH count.
2000-10-26 17:38:24 -04:00
/*-------------------------------------------------------------------------
*
* nodeLimit.h
*
*
*
Update copyright for 2024 Reported-by: Michael Paquier Discussion: https://postgr.es/m/ZZKTDPxBBMt3C0J9@paquier.xyz Backpatch-through: 12
2024-01-03 20:49:05 -05:00
* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
Re-implement LIMIT/OFFSET as a plan node type, instead of a hack in ExecutorRun. This allows LIMIT to work in a view. Also, LIMIT in a cursor declaration will behave in a reasonable fashion, whereas before it was overridden by the FETCH count.
2000-10-26 17:38:24 -04:00
* Portions Copyright (c) 1994, Regents of the University of California
*
Remove cvs keywords from all files.
2010-09-20 16:08:53 -04:00
* src/include/executor/nodeLimit.h
Re-implement LIMIT/OFFSET as a plan node type, instead of a hack in ExecutorRun. This allows LIMIT to work in a view. Also, LIMIT in a cursor declaration will behave in a reasonable fashion, whereas before it was overridden by the FETCH count.
2000-10-26 17:38:24 -04:00
*
*-------------------------------------------------------------------------
*/
#ifndef NODELIMIT_H
#define NODELIMIT_H
Phase 1 of read-only-plans project: cause executor state nodes to point to plan nodes, not vice-versa. All executor state nodes now inherit from struct PlanState. Copying of plan trees has been simplified by not storing a list of SubPlans in Plan nodes (eliminating duplicate links). The executor still needs such a list, but it can build it during ExecutorStart since it has to scan the plan tree anyway. No initdb forced since no stored-on-disk structures changed, but you will need a full recompile because of node-numbering changes.
2002-12-05 10:50:39 -05:00
#include "nodes/execnodes.h"
Re-implement LIMIT/OFFSET as a plan node type, instead of a hack in ExecutorRun. This allows LIMIT to work in a view. Also, LIMIT in a cursor declaration will behave in a reasonable fashion, whereas before it was overridden by the FETCH count.
2000-10-26 17:38:24 -04:00
Extend the ExecInitNode API so that plan nodes receive a set of flag bits indicating which optional capabilities can actually be exercised at runtime. This will allow Sort and Material nodes, and perhaps later other nodes, to avoid unnecessary overhead in common cases. This commit just adds the infrastructure and arranges to pass the correct flag values down to plan nodes; none of the actual optimizations are here yet. I'm committing this separately in case anyone wants to measure the added overhead. (It should be negligible.) Simon Riggs and Tom Lane
2006-02-27 23:10:28 -05:00
extern LimitState *ExecInitLimit(Limit *node, EState *estate, int eflags);
Phase 1 of read-only-plans project: cause executor state nodes to point to plan nodes, not vice-versa. All executor state nodes now inherit from struct PlanState. Copying of plan trees has been simplified by not storing a list of SubPlans in Plan nodes (eliminating duplicate links). The executor still needs such a list, but it can build it during ExecutorStart since it has to scan the plan tree anyway. No initdb forced since no stored-on-disk structures changed, but you will need a full recompile because of node-numbering changes.
2002-12-05 10:50:39 -05:00
extern void ExecEndLimit(LimitState *node);
Make NestLoop plan nodes pass outer-relation variables into their inner relation using the general PARAM_EXEC executor parameter mechanism, rather than the ad-hoc kluge of passing the outer tuple down through ExecReScan. The previous method was hard to understand and could never be extended to handle parameters coming from multiple join levels. This patch doesn't change the set of possible plans nor have any significant performance effect, but it's necessary infrastructure for future generalization of the concept of an inner indexscan plan. ExecReScan's second parameter is now unused, so it's removed.
2010-07-12 13:01:06 -04:00
extern void ExecReScanLimit(LimitState *node);
Another pgindent run. Fixes enum indenting, and improves #endif spacing. Also adds space for one-line comments.
2001-10-28 01:26:15 -05:00
Re-implement LIMIT/OFFSET as a plan node type, instead of a hack in ExecutorRun. This allows LIMIT to work in a view. Also, LIMIT in a cursor declaration will behave in a reasonable fashion, whereas before it was overridden by the FETCH count.
2000-10-26 17:38:24 -04:00
#endif /* NODELIMIT_H */
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