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TABLESAMPLE, SQL Standard and extensible
Add a TABLESAMPLE clause to SELECT statements that allows user to specify random BERNOULLI sampling or block level SYSTEM sampling. Implementation allows for extensible sampling functions to be written, using a standard API. Basic version follows SQLStandard exactly. Usable concrete use cases for the sampling API follow in later commits. Petr Jelinek Reviewed by Michael Paquier and Simon Riggs
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src/include/executor/nodeSamplescan.h
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24
src/include/executor/nodeSamplescan.h
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/*-------------------------------------------------------------------------
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*
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* nodeSamplescan.h
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*
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*
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*
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* Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/executor/nodeSamplescan.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef NODESAMPLESCAN_H
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#define NODESAMPLESCAN_H
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#include "nodes/execnodes.h"
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extern SampleScanState *ExecInitSampleScan(SampleScan *node, EState *estate, int eflags);
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extern TupleTableSlot *ExecSampleScan(SampleScanState *node);
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extern void ExecEndSampleScan(SampleScanState *node);
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extern void ExecReScanSampleScan(SampleScanState *node);
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#endif /* NODESAMPLESCAN_H */
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