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| author | Simon Riggs <simon@2ndQuadrant.com> | 2015-05-15 14:37:10 -0400 |
|---|---|---|
| committer | Simon Riggs <simon@2ndQuadrant.com> | 2015-05-15 14:37:10 -0400 |
| commit | f6d208d6e51810c73f0e02c477984a6b44627f11 (patch) | |
| tree | 99d540d0b7bda73ff60479f15444f554403d4679 /src/backend/nodes/readfuncs.c | |
| parent | 11a83bbedd73800db70f6f2af5a8eb10d15d39d7 (diff) | |
| download | postgresql-f6d208d6e51810c73f0e02c477984a6b44627f11.tar.gz postgresql-f6d208d6e51810c73f0e02c477984a6b44627f11.zip | |
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
Diffstat (limited to 'src/backend/nodes/readfuncs.c')
| -rw-r--r-- | src/backend/nodes/readfuncs.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c index 8136306e1e5..c8fb894a75a 100644 --- a/src/backend/nodes/readfuncs.c +++ b/src/backend/nodes/readfuncs.c @@ -352,6 +352,46 @@ _readCommonTableExpr(void) } /* + * _readRangeTableSample + */ +static RangeTableSample * +_readRangeTableSample(void) +{ + READ_LOCALS(RangeTableSample); + + READ_NODE_FIELD(relation); + READ_STRING_FIELD(method); + READ_NODE_FIELD(repeatable); + READ_NODE_FIELD(args); + + READ_DONE(); +} + +/* + * _readTableSampleClause + */ +static TableSampleClause * +_readTableSampleClause(void) +{ + READ_LOCALS(TableSampleClause); + + READ_OID_FIELD(tsmid); + READ_BOOL_FIELD(tsmseqscan); + READ_BOOL_FIELD(tsmpagemode); + READ_OID_FIELD(tsminit); + READ_OID_FIELD(tsmnextblock); + READ_OID_FIELD(tsmnexttuple); + READ_OID_FIELD(tsmexaminetuple); + READ_OID_FIELD(tsmend); + READ_OID_FIELD(tsmreset); + READ_OID_FIELD(tsmcost); + READ_NODE_FIELD(repeatable); + READ_NODE_FIELD(args); + + READ_DONE(); +} + +/* * _readSetOperationStmt */ static SetOperationStmt * @@ -1255,6 +1295,7 @@ _readRangeTblEntry(void) case RTE_RELATION: READ_OID_FIELD(relid); READ_CHAR_FIELD(relkind); + READ_NODE_FIELD(tablesample); break; case RTE_SUBQUERY: READ_NODE_FIELD(subquery); @@ -1351,6 +1392,10 @@ parseNodeString(void) return_value = _readRowMarkClause(); else if (MATCH("COMMONTABLEEXPR", 15)) return_value = _readCommonTableExpr(); + else if (MATCH("RANGETABLESAMPLE", 16)) + return_value = _readRangeTableSample(); + else if (MATCH("TABLESAMPLECLAUSE", 17)) + return_value = _readTableSampleClause(); else if (MATCH("SETOPERATIONSTMT", 16)) return_value = _readSetOperationStmt(); else if (MATCH("ALIAS", 5)) |