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Refactor crosstab() to build and return a tuplestore instead of using
value-per-call mode. This should be more efficient in normal usage, but the real problem with the prior coding was that it returned with a SPI call still active. That could cause problems if execution was interleaved with anything else that might use SPI.
This commit is contained in:
Tom Lane
parent
76cc2fe6a1
commit
cf407f164e
@ -1,5 +1,5 @@
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/*
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* $PostgreSQL: pgsql/contrib/tablefunc/tablefunc.c,v 1.56 2008/11/30 23:23:52 tgl Exp $
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* $PostgreSQL: pgsql/contrib/tablefunc/tablefunc.c,v 1.57 2008/12/01 01:30:18 tgl Exp $
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*
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*
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* tablefunc
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@ -94,12 +94,6 @@ typedef struct
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bool use_carry; /* use second generated value */
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} normal_rand_fctx;
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typedef struct
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{
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SPITupleTable *spi_tuptable; /* sql results from user query */
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char *lastrowid; /* rowid of the last tuple sent */
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} crosstab_fctx;
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#define xpfree(var_) \
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do { \
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if (var_ != NULL) \
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@ -356,30 +350,36 @@ PG_FUNCTION_INFO_V1(crosstab);
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Datum
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crosstab(PG_FUNCTION_ARGS)
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{
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FuncCallContext *funcctx;
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TupleDesc ret_tupdesc;
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char *sql = text_to_cstring(PG_GETARG_TEXT_PP(0));
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ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
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Tuplestorestate *tupstore;
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TupleDesc tupdesc;
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int call_cntr;
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int max_calls;
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AttInMetadata *attinmeta;
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SPITupleTable *spi_tuptable = NULL;
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SPITupleTable *spi_tuptable;
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TupleDesc spi_tupdesc;
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char *lastrowid = NULL;
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crosstab_fctx *fctx;
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bool firstpass;
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char *lastrowid;
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int i;
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int num_categories;
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bool firstpass = false;
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MemoryContext per_query_ctx;
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MemoryContext oldcontext;
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/* stuff done only on the first call of the function */
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if (SRF_IS_FIRSTCALL())
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{
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char *sql = text_to_cstring(PG_GETARG_TEXT_PP(0));
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TupleDesc tupdesc;
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int ret;
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int proc;
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/* create a function context for cross-call persistence */
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funcctx = SRF_FIRSTCALL_INIT();
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/* check to see if caller supports us returning a tuplestore */
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if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("set-valued function called in context that cannot accept a set")));
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if (!(rsinfo->allowedModes & SFRM_Materialize))
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("materialize mode required, but it is not " \
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"allowed in this context")));
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per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
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/* Connect to SPI manager */
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if ((ret = SPI_connect()) < 0)
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@ -390,9 +390,14 @@ crosstab(PG_FUNCTION_ARGS)
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ret = SPI_execute(sql, true, 0);
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proc = SPI_processed;
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/* Check for qualifying tuples */
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if ((ret == SPI_OK_SELECT) && (proc > 0))
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/* If no qualifying tuples, fall out early */
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if (ret != SPI_OK_SELECT || proc <= 0)
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{
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SPI_finish();
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rsinfo->isDone = ExprEndResult;
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PG_RETURN_NULL();
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}
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spi_tuptable = SPI_tuptable;
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spi_tupdesc = spi_tuptable->tupdesc;
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@ -413,13 +418,6 @@ crosstab(PG_FUNCTION_ARGS)
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errmsg("invalid source data SQL statement"),
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errdetail("The provided SQL must return 3 "
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"columns: rowid, category, and values.")));
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}
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else
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{
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/* no qualifying tuples */
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SPI_finish();
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SRF_RETURN_DONE(funcctx);
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}
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/* get a tuple descriptor for our result type */
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switch (get_call_result_type(fcinfo, NULL, &tupdesc))
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@ -451,75 +449,42 @@ crosstab(PG_FUNCTION_ARGS)
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"incompatible")));
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/*
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* switch to memory context appropriate for multiple function calls
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* switch to long-lived memory context
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*/
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oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
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oldcontext = MemoryContextSwitchTo(per_query_ctx);
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/* make sure we have a persistent copy of the tupdesc */
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/* make sure we have a persistent copy of the result tupdesc */
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tupdesc = CreateTupleDescCopy(tupdesc);
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/* initialize our tuplestore in long-lived context */
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tupstore =
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tuplestore_begin_heap(rsinfo->allowedModes & SFRM_Materialize_Random,
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false, work_mem);
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MemoryContextSwitchTo(oldcontext);
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/*
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* Generate attribute metadata needed later to produce tuples from raw
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* C strings
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*/
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attinmeta = TupleDescGetAttInMetadata(tupdesc);
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funcctx->attinmeta = attinmeta;
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/* allocate memory for user context */
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fctx = (crosstab_fctx *) palloc(sizeof(crosstab_fctx));
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/*
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* Save spi data for use across calls
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*/
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fctx->spi_tuptable = spi_tuptable;
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fctx->lastrowid = NULL;
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funcctx->user_fctx = fctx;
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/* total number of tuples to be returned */
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funcctx->max_calls = proc;
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MemoryContextSwitchTo(oldcontext);
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firstpass = true;
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}
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/* stuff done on every call of the function */
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funcctx = SRF_PERCALL_SETUP();
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/*
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* initialize per-call variables
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*/
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call_cntr = funcctx->call_cntr;
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max_calls = funcctx->max_calls;
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/* user context info */
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fctx = (crosstab_fctx *) funcctx->user_fctx;
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lastrowid = fctx->lastrowid;
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spi_tuptable = fctx->spi_tuptable;
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/* the sql tuple */
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spi_tupdesc = spi_tuptable->tupdesc;
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/* attribute return type and return tuple description */
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attinmeta = funcctx->attinmeta;
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ret_tupdesc = attinmeta->tupdesc;
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/* total number of tuples to be examined */
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max_calls = proc;
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/* the return tuple always must have 1 rowid + num_categories columns */
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num_categories = ret_tupdesc->natts - 1;
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num_categories = tupdesc->natts - 1;
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if (call_cntr < max_calls) /* do when there is more left to send */
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firstpass = true;
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lastrowid = NULL;
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for (call_cntr = 0; call_cntr < max_calls; call_cntr++)
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{
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HeapTuple tuple;
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Datum result;
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char **values;
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bool skip_tuple = false;
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char **values;
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while (true)
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{
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/* allocate space */
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values = (char **) palloc((1 + num_categories) * sizeof(char *));
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/* and make sure it's clear */
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memset(values, '\0', (1 + num_categories) * sizeof(char *));
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/* allocate and zero space */
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values = (char **) palloc0((1 + num_categories) * sizeof(char *));
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/*
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* now loop through the sql results and assign each value in
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@ -528,7 +493,7 @@ crosstab(PG_FUNCTION_ARGS)
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for (i = 0; i < num_categories; i++)
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{
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HeapTuple spi_tuple;
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char *rowid = NULL;
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char *rowid;
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/* see if we've gone too far already */
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if (call_cntr >= max_calls)
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@ -554,13 +519,14 @@ crosstab(PG_FUNCTION_ARGS)
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*/
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if (!firstpass && xstreq(lastrowid, rowid))
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{
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xpfree(rowid);
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skip_tuple = true;
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break;
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}
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}
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/*
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* If rowid hasn't changed on us, continue building the ouput
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* If rowid hasn't changed on us, continue building the output
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* tuple.
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*/
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if (xstreq(rowid, values[0]))
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@ -576,11 +542,12 @@ crosstab(PG_FUNCTION_ARGS)
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/*
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* increment the counter since we consume a row for each
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* category, but not for last pass because the API will do
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* that for us
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* category, but not for last pass because the outer loop
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* will do that for us
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*/
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if (i < (num_categories - 1))
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call_cntr = ++funcctx->call_cntr;
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call_cntr++;
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xpfree(rowid);
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}
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else
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{
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@ -589,71 +556,48 @@ crosstab(PG_FUNCTION_ARGS)
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* to decrement the counter since this sql result row
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* doesn't belong to the current output tuple.
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*/
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call_cntr = --funcctx->call_cntr;
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call_cntr--;
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xpfree(rowid);
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break;
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}
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xpfree(rowid);
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}
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/*
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* switch to memory context appropriate for multiple function
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* calls
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*/
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oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
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xpfree(fctx->lastrowid);
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xpstrdup(fctx->lastrowid, values[0]);
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lastrowid = fctx->lastrowid;
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MemoryContextSwitchTo(oldcontext);
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if (!skip_tuple)
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{
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HeapTuple tuple;
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/* build the tuple */
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tuple = BuildTupleFromCStrings(attinmeta, values);
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/* make the tuple into a datum */
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result = HeapTupleGetDatum(tuple);
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/* switch to appropriate context while storing the tuple */
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oldcontext = MemoryContextSwitchTo(per_query_ctx);
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tuplestore_puttuple(tupstore, tuple);
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MemoryContextSwitchTo(oldcontext);
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heap_freetuple(tuple);
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}
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/* Remember current rowid */
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xpfree(lastrowid);
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xpstrdup(lastrowid, values[0]);
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firstpass = false;
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/* Clean up */
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for (i = 0; i < num_categories + 1; i++)
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if (values[i] != NULL)
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xpfree(values[i]);
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xpfree(values);
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SRF_RETURN_NEXT(funcctx, result);
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pfree(values[i]);
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pfree(values);
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}
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else
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{
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/*
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* Skipping this tuple entirely, but we need to advance the
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* counter like the API would if we had returned one.
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*/
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call_cntr = ++funcctx->call_cntr;
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/* we'll start over at the top */
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xpfree(values);
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/* let the caller know we're sending back a tuplestore */
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rsinfo->returnMode = SFRM_Materialize;
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rsinfo->setResult = tupstore;
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rsinfo->setDesc = tupdesc;
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/* see if we've gone too far already */
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if (call_cntr >= max_calls)
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{
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/* release SPI related resources */
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/* release SPI related resources (and return to caller's context) */
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SPI_finish();
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SRF_RETURN_DONE(funcctx);
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}
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/* need to reset this before the next tuple is started */
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skip_tuple = false;
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}
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}
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}
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else
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/* do when there is no more left */
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{
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/* release SPI related resources */
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SPI_finish();
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SRF_RETURN_DONE(funcctx);
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}
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return (Datum) 0;
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}
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/*
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@ -1613,6 +1557,10 @@ compatCrosstabTupleDescs(TupleDesc ret_tupdesc, TupleDesc sql_tupdesc)
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Form_pg_attribute sql_attr;
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Oid sql_atttypid;
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if (ret_tupdesc->natts < 2 ||
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sql_tupdesc->natts < 3)
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return false;
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/* check the rowid types match */
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ret_atttypid = ret_tupdesc->attrs[0]->atttypid;
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sql_atttypid = sql_tupdesc->attrs[0]->atttypid;
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