mirror of https://github.com/citusdata/citus.git
124 lines
3.4 KiB
C
124 lines
3.4 KiB
C
/*-------------------------------------------------------------------------
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*
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* foreign_key_relationship_query.c
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*
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* This file contains UDFs for getting foreign constraint relationship between
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* distributed tables.
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*
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* Copyright (c) Citus Data, Inc.
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "fmgr.h"
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#include "funcapi.h"
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#include "distributed/metadata_cache.h"
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/* these functions are only exported in the regression tests */
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PG_FUNCTION_INFO_V1(get_referencing_relation_id_list);
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PG_FUNCTION_INFO_V1(get_referenced_relation_id_list);
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/*
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* get_referencing_relation_id_list returns the list of table oids that is referencing
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* by given oid recursively. It uses the list cached in the distributed table cache
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* entry.
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*/
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Datum
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get_referencing_relation_id_list(PG_FUNCTION_ARGS)
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{
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FuncCallContext *functionContext = NULL;
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ListCell *foreignRelationCell = NULL;
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CheckCitusVersion(ERROR);
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/* for the first we call this UDF, we need to populate the result to return set */
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if (SRF_IS_FIRSTCALL())
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{
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Oid relationId = PG_GETARG_OID(0);
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DistTableCacheEntry *cacheEntry = DistributedTableCacheEntry(relationId);
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List *refList = cacheEntry->referencingRelationsViaForeignKey;
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/* create a function context for cross-call persistence */
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functionContext = SRF_FIRSTCALL_INIT();
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foreignRelationCell = list_head(refList);
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functionContext->user_fctx = foreignRelationCell;
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}
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/*
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* On every call to this function, we get the current position in the
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* statement list. We then iterate to the next position in the list and
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* return the current statement, if we have not yet reached the end of
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* list.
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*/
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functionContext = SRF_PERCALL_SETUP();
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foreignRelationCell = (ListCell *) functionContext->user_fctx;
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if (foreignRelationCell != NULL)
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{
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Oid refId = lfirst_oid(foreignRelationCell);
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functionContext->user_fctx = lnext(foreignRelationCell);
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SRF_RETURN_NEXT(functionContext, PointerGetDatum(refId));
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}
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else
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{
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SRF_RETURN_DONE(functionContext);
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}
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}
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/*
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* get_referenced_relation_id_list returns the list of table oids that is referenced
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* by given oid recursively. It uses the list cached in the distributed table cache
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* entry.
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*/
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Datum
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get_referenced_relation_id_list(PG_FUNCTION_ARGS)
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{
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FuncCallContext *functionContext = NULL;
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ListCell *foreignRelationCell = NULL;
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CheckCitusVersion(ERROR);
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/* for the first we call this UDF, we need to populate the result to return set */
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if (SRF_IS_FIRSTCALL())
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{
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Oid relationId = PG_GETARG_OID(0);
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DistTableCacheEntry *cacheEntry = DistributedTableCacheEntry(relationId);
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List *refList = cacheEntry->referencedRelationsViaForeignKey;
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/* create a function context for cross-call persistence */
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functionContext = SRF_FIRSTCALL_INIT();
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foreignRelationCell = list_head(refList);
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functionContext->user_fctx = foreignRelationCell;
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}
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/*
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* On every call to this function, we get the current position in the
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* statement list. We then iterate to the next position in the list and
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* return the current statement, if we have not yet reached the end of
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* list.
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*/
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functionContext = SRF_PERCALL_SETUP();
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foreignRelationCell = (ListCell *) functionContext->user_fctx;
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if (foreignRelationCell != NULL)
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{
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Oid refId = lfirst_oid(foreignRelationCell);
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functionContext->user_fctx = lnext(foreignRelationCell);
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SRF_RETURN_NEXT(functionContext, PointerGetDatum(refId));
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}
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else
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{
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SRF_RETURN_DONE(functionContext);
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}
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}
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