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After further thought about support for gathering stats on functional
indexes, it seems like we ought to put another layer of indirection between the compute_stats functions and the actual data storage. This would allow us to compute the values on-the-fly, for example.
This commit is contained in:
Tom Lane
parent
1a4652333b
commit
8787bc8ef3
@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.68 2004/02/12 23:41:02 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.69 2004/02/13 06:39:49 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -52,6 +52,7 @@ static double init_selection_state(int n);
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static double select_next_random_record(double t, int n, double *stateptr);
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static int compare_rows(const void *a, const void *b);
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static void update_attstats(Oid relid, int natts, VacAttrStats **vacattrstats);
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static Datum std_fetch_func(VacAttrStatsP stats, int rownum, bool *isNull);
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static bool std_typanalyze(VacAttrStats *stats);
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@ -259,12 +260,14 @@ analyze_rel(Oid relid, VacuumStmt *vacstmt)
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old_context = MemoryContextSwitchTo(col_context);
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for (i = 0; i < attr_cnt; i++)
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{
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(*vacattrstats[i]->compute_stats) (vacattrstats[i],
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vacattrstats[i]->tupattnum,
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onerel->rd_att,
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totalrows,
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rows,
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numrows);
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VacAttrStats *stats = vacattrstats[i];
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stats->rows = rows;
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stats->tupDesc = onerel->rd_att;
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(*stats->compute_stats) (stats,
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std_fetch_func,
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numrows,
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totalrows);
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MemoryContextResetAndDeleteChildren(col_context);
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}
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MemoryContextSwitchTo(old_context);
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@ -861,6 +864,22 @@ update_attstats(Oid relid, int natts, VacAttrStats **vacattrstats)
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heap_close(sd, RowExclusiveLock);
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}
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/*
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* Standard fetch function for use by compute_stats subroutines.
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*
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* This exists to provide some insulation between compute_stats routines
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* and the actual storage of the sample data.
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*/
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static Datum
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std_fetch_func(VacAttrStatsP stats, int rownum, bool *isNull)
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{
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int attnum = stats->tupattnum;
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HeapTuple tuple = stats->rows[rownum];
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TupleDesc tupDesc = stats->tupDesc;
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return heap_getattr(tuple, attnum, tupDesc, isNull);
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}
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/*==========================================================================
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*
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@ -915,12 +934,14 @@ static SortFunctionKind datumCmpFnKind;
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static int *datumCmpTupnoLink;
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static void compute_minimal_stats(VacAttrStats *stats, int attnum,
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TupleDesc tupDesc, double totalrows,
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HeapTuple *rows, int numrows);
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static void compute_scalar_stats(VacAttrStats *stats, int attnum,
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TupleDesc tupDesc, double totalrows,
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HeapTuple *rows, int numrows);
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static void compute_minimal_stats(VacAttrStatsP stats,
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AnalyzeAttrFetchFunc fetchfunc,
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int samplerows,
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double totalrows);
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static void compute_scalar_stats(VacAttrStatsP stats,
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AnalyzeAttrFetchFunc fetchfunc,
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int samplerows,
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double totalrows);
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static int compare_scalars(const void *a, const void *b);
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static int compare_mcvs(const void *a, const void *b);
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@ -1024,9 +1045,10 @@ std_typanalyze(VacAttrStats *stats)
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* depend mainly on the length of the list we are willing to keep.
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*/
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static void
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compute_minimal_stats(VacAttrStats *stats, int attnum,
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TupleDesc tupDesc, double totalrows,
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HeapTuple *rows, int numrows)
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compute_minimal_stats(VacAttrStatsP stats,
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AnalyzeAttrFetchFunc fetchfunc,
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int samplerows,
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double totalrows)
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{
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int i;
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int null_cnt = 0;
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@ -1061,9 +1083,8 @@ compute_minimal_stats(VacAttrStats *stats, int attnum,
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fmgr_info(mystats->eqfunc, &f_cmpeq);
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for (i = 0; i < numrows; i++)
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for (i = 0; i < samplerows; i++)
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{
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HeapTuple tuple = rows[i];
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Datum value;
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bool isnull;
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bool match;
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@ -1072,7 +1093,7 @@ compute_minimal_stats(VacAttrStats *stats, int attnum,
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vacuum_delay_point();
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value = heap_getattr(tuple, attnum, tupDesc, &isnull);
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value = fetchfunc(stats, i, &isnull);
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/* Check for null/nonnull */
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if (isnull)
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@ -1166,7 +1187,7 @@ compute_minimal_stats(VacAttrStats *stats, int attnum,
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stats->stats_valid = true;
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/* Do the simple null-frac and width stats */
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stats->stanullfrac = (double) null_cnt / (double) numrows;
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stats->stanullfrac = (double) null_cnt / (double) samplerows;
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if (is_varwidth)
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stats->stawidth = total_width / (double) nonnull_cnt;
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else
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@ -1222,10 +1243,10 @@ compute_minimal_stats(VacAttrStats *stats, int attnum,
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denom,
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stadistinct;
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numer = (double) numrows *(double) d;
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numer = (double) samplerows *(double) d;
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denom = (double) (numrows - f1) +
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(double) f1 *(double) numrows / totalrows;
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denom = (double) (samplerows - f1) +
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(double) f1 *(double) samplerows / totalrows;
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stadistinct = numer / denom;
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/* Clamp to sane range in case of roundoff error */
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@ -1270,7 +1291,7 @@ compute_minimal_stats(VacAttrStats *stats, int attnum,
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if (ndistinct < 0)
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ndistinct = -ndistinct * totalrows;
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/* estimate # of occurrences in sample of a typical value */
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avgcount = (double) numrows / ndistinct;
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avgcount = (double) samplerows / ndistinct;
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/* set minimum threshold count to store a value */
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mincount = avgcount * 1.25;
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if (mincount < 2)
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@ -1303,7 +1324,7 @@ compute_minimal_stats(VacAttrStats *stats, int attnum,
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mcv_values[i] = datumCopy(track[i].value,
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stats->attr->attbyval,
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stats->attr->attlen);
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mcv_freqs[i] = (double) track[i].count / (double) numrows;
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mcv_freqs[i] = (double) track[i].count / (double) samplerows;
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}
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MemoryContextSwitchTo(old_context);
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@ -1333,9 +1354,10 @@ compute_minimal_stats(VacAttrStats *stats, int attnum,
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* data values into order.
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*/
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static void
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compute_scalar_stats(VacAttrStats *stats, int attnum,
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TupleDesc tupDesc, double totalrows,
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HeapTuple *rows, int numrows)
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compute_scalar_stats(VacAttrStatsP stats,
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AnalyzeAttrFetchFunc fetchfunc,
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int samplerows,
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double totalrows)
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{
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int i;
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int null_cnt = 0;
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@ -1359,23 +1381,22 @@ compute_scalar_stats(VacAttrStats *stats, int attnum,
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int num_bins = stats->attr->attstattarget;
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StdAnalyzeData *mystats = (StdAnalyzeData *) stats->extra_data;
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values = (ScalarItem *) palloc(numrows * sizeof(ScalarItem));
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tupnoLink = (int *) palloc(numrows * sizeof(int));
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values = (ScalarItem *) palloc(samplerows * sizeof(ScalarItem));
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tupnoLink = (int *) palloc(samplerows * sizeof(int));
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track = (ScalarMCVItem *) palloc(num_mcv * sizeof(ScalarMCVItem));
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SelectSortFunction(mystats->ltopr, &cmpFn, &cmpFnKind);
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fmgr_info(cmpFn, &f_cmpfn);
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/* Initial scan to find sortable values */
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for (i = 0; i < numrows; i++)
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for (i = 0; i < samplerows; i++)
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{
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HeapTuple tuple = rows[i];
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Datum value;
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bool isnull;
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vacuum_delay_point();
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value = heap_getattr(tuple, attnum, tupDesc, &isnull);
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value = fetchfunc(stats, i, &isnull);
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/* Check for null/nonnull */
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if (isnull)
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@ -1505,7 +1526,7 @@ compute_scalar_stats(VacAttrStats *stats, int attnum,
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stats->stats_valid = true;
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/* Do the simple null-frac and width stats */
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stats->stanullfrac = (double) null_cnt / (double) numrows;
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stats->stanullfrac = (double) null_cnt / (double) samplerows;
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if (is_varwidth)
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stats->stawidth = total_width / (double) nonnull_cnt;
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else
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@ -1546,10 +1567,10 @@ compute_scalar_stats(VacAttrStats *stats, int attnum,
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denom,
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stadistinct;
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numer = (double) numrows *(double) d;
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numer = (double) samplerows *(double) d;
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denom = (double) (numrows - f1) +
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(double) f1 *(double) numrows / totalrows;
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denom = (double) (samplerows - f1) +
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(double) f1 *(double) samplerows / totalrows;
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stadistinct = numer / denom;
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/* Clamp to sane range in case of roundoff error */
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@ -1599,13 +1620,13 @@ compute_scalar_stats(VacAttrStats *stats, int attnum,
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if (ndistinct < 0)
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ndistinct = -ndistinct * totalrows;
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/* estimate # of occurrences in sample of a typical value */
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avgcount = (double) numrows / ndistinct;
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avgcount = (double) samplerows / ndistinct;
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/* set minimum threshold count to store a value */
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mincount = avgcount * 1.25;
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if (mincount < 2)
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mincount = 2;
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/* don't let threshold exceed 1/K, however */
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maxmincount = (double) numrows / (double) num_bins;
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maxmincount = (double) samplerows / (double) num_bins;
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if (mincount > maxmincount)
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mincount = maxmincount;
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if (num_mcv > track_cnt)
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@ -1636,7 +1657,7 @@ compute_scalar_stats(VacAttrStats *stats, int attnum,
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mcv_values[i] = datumCopy(values[track[i].first].value,
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stats->attr->attbyval,
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stats->attr->attlen);
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mcv_freqs[i] = (double) track[i].count / (double) numrows;
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mcv_freqs[i] = (double) track[i].count / (double) samplerows;
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}
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MemoryContextSwitchTo(old_context);
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2003, 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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* $PostgreSQL: pgsql/src/include/commands/vacuum.h,v 1.49 2004/02/12 23:41:04 tgl Exp $
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* $PostgreSQL: pgsql/src/include/commands/vacuum.h,v 1.50 2004/02/13 06:39:49 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -40,18 +40,18 @@
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* and must return TRUE to continue analysis, FALSE to skip analysis of this
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* column. In the TRUE case it must set the compute_stats and minrows fields,
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* and can optionally set extra_data to pass additional info to compute_stats.
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* minrows is its request for the minimum number of sample rows to be gathered
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* (but note this request might not be honored, eg if there are fewer rows
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* than that in the table).
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*
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* The compute_stats routine will be called after sample rows have been
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* gathered. Aside from this struct, it is passed:
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* attnum: attribute number within the supplied tuples
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* tupDesc: tuple descriptor for the supplied tuples
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* fetchfunc: a function for accessing the column values from the
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* sample rows
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* samplerows: the number of sample tuples
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* totalrows: estimated total number of rows in relation
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* rows: an array of the sample tuples
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* numrows: the number of sample tuples
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* Note that the passed attnum and tupDesc could possibly be different from
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* what one would expect by looking at the pg_attribute row. It is important
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* to use these values for extracting attribute values from the given rows
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* (and not for any other purpose).
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* The fetchfunc may be called with rownum running from 0 to samplerows-1.
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* It returns a Datum and an isNull flag.
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*
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* compute_stats should set stats_valid TRUE if it is able to compute
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* any useful statistics. If it does, the remainder of the struct holds
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@ -60,6 +60,11 @@
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* be CurrentMemoryContext when compute_stats is called.
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*----------
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*/
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typedef struct VacAttrStats *VacAttrStatsP;
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typedef Datum (*AnalyzeAttrFetchFunc) (VacAttrStatsP stats, int rownum,
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bool *isNull);
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typedef struct VacAttrStats
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{
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/*
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@ -74,9 +79,10 @@ typedef struct VacAttrStats
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* These fields must be filled in by the typanalyze routine,
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* unless it returns FALSE.
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*/
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void (*compute_stats) (struct VacAttrStats *stats, int attnum,
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TupleDesc tupDesc, double totalrows,
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HeapTuple *rows, int numrows);
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void (*compute_stats) (VacAttrStatsP stats,
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AnalyzeAttrFetchFunc fetchfunc,
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int samplerows,
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double totalrows);
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int minrows; /* Minimum # of rows wanted for stats */
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void *extra_data; /* for extra type-specific data */
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@ -100,6 +106,8 @@ typedef struct VacAttrStats
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* be looked at by type-specific functions.
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*/
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int tupattnum; /* attribute number within tuples */
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HeapTuple *rows; /* access info for fetch function */
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TupleDesc tupDesc;
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} VacAttrStats;
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