--- /dev/null
+/*-------------------------------------------------------------------------
+ *
+ * analyze.c
+ * the postgres optimizer analyzer
+ *
+ * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ * $Header: /cvsroot/pgsql/src/backend/commands/analyze.c,v 1.1 2000/05/29 17:44:17 momjian Exp $
+ *
+
+ *-------------------------------------------------------------------------
+ */
+#include <sys/types.h>
+#include <sys/file.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "postgres.h"
+
+#include "access/heapam.h"
+#include "catalog/catname.h"
+#include "catalog/indexing.h"
+#include "catalog/pg_operator.h"
+#include "catalog/pg_statistic.h"
+#include "catalog/pg_type.h"
+#include "commands/vacuum.h"
+#include "miscadmin.h"
+#include "parser/parse_oper.h"
+#include "tcop/tcopprot.h"
+#include "utils/acl.h"
+#include "utils/builtins.h"
+#include "utils/fmgroids.h"
+#include "utils/inval.h"
+#include "utils/syscache.h"
+
+#define swapLong(a,b) {long tmp; tmp=a; a=b; b=tmp;}
+#define swapInt(a,b) {int tmp; tmp=a; a=b; b=tmp;}
+#define swapDatum(a,b) {Datum tmp; tmp=a; a=b; b=tmp;}
+#define VacAttrStatsEqValid(stats) ( stats->f_cmpeq.fn_addr != NULL )
+#define VacAttrStatsLtGtValid(stats) ( stats->f_cmplt.fn_addr != NULL && \
+ stats->f_cmpgt.fn_addr != NULL && \
+ RegProcedureIsValid(stats->outfunc) )
+
+
+static void attr_stats(Relation onerel, int attr_cnt, VacAttrStats *vacattrstats, HeapTuple tuple);
+static void bucketcpy(Form_pg_attribute attr, Datum value, Datum *bucket, int *bucket_len);
+static void update_attstats(Oid relid, int natts, VacAttrStats *vacattrstats);
+static void del_stats(Oid relid, int attcnt, int *attnums);
+
+
+/*
+ * analyze_rel() -- analyze relation
+ */
+void
+analyze_rel(Oid relid, List *anal_cols2, int MESSAGE_LEVEL)
+{
+ HeapTuple tuple,
+ typetuple;
+ Relation onerel;
+ int32 i;
+ int attr_cnt,
+ *attnums = NULL;
+ Form_pg_attribute *attr;
+ VacAttrStats *vacattrstats;
+ HeapScanDesc scan;
+
+ StartTransactionCommand();
+
+ /*
+ * Check for user-requested abort. Note we want this to be inside a
+ * transaction, so xact.c doesn't issue useless NOTICE.
+ */
+ if (QueryCancel)
+ CancelQuery();
+
+ /*
+ * Race condition -- if the pg_class tuple has gone away since the
+ * last time we saw it, we don't need to vacuum it.
+ */
+ tuple = SearchSysCacheTuple(RELOID,
+ ObjectIdGetDatum(relid),
+ 0, 0, 0);
+ /*
+ * We can VACUUM ANALYZE any table except pg_statistic.
+ * see update_relstats
+ */
+ if (!HeapTupleIsValid(tuple) ||
+ strcmp(NameStr(((Form_pg_class) GETSTRUCT(tuple))->relname),
+ StatisticRelationName) == 0)
+ {
+ CommitTransactionCommand();
+ return;
+ }
+
+ onerel = heap_open(relid, AccessShareLock);
+
+#ifndef NO_SECURITY
+ if (!pg_ownercheck(GetPgUserName(), RelationGetRelationName(onerel),
+ RELNAME))
+ {
+ /* we already did an elog during vacuum
+ elog(NOTICE, "Skipping \"%s\" --- only table owner can VACUUM it",
+ RelationGetRelationName(onerel));
+ */
+ heap_close(onerel, AccessExclusiveLock);
+ CommitTransactionCommand();
+ return;
+ }
+#endif
+
+ elog(MESSAGE_LEVEL, "Analyzing...");
+
+ attr_cnt = onerel->rd_att->natts;
+ attr = onerel->rd_att->attrs;
+
+ if (anal_cols2 != NIL)
+ {
+ int tcnt = 0;
+ List *le;
+
+ if (length(anal_cols2) > attr_cnt)
+ elog(ERROR, "vacuum: too many attributes specified for relation %s",
+ RelationGetRelationName(onerel));
+ attnums = (int *) palloc(attr_cnt * sizeof(int));
+ foreach(le, anal_cols2)
+ {
+ char *col = (char *) lfirst(le);
+
+ for (i = 0; i < attr_cnt; i++)
+ {
+ if (namestrcmp(&(attr[i]->attname), col) == 0)
+ break;
+ }
+ if (i < attr_cnt) /* found */
+ attnums[tcnt++] = i;
+ else
+ {
+ elog(ERROR, "vacuum: there is no attribute %s in %s",
+ col, RelationGetRelationName(onerel));
+ }
+ }
+ attr_cnt = tcnt;
+ }
+
+ vacattrstats = (VacAttrStats *) palloc(attr_cnt * sizeof(VacAttrStats));
+
+ for (i = 0; i < attr_cnt; i++)
+ {
+ Operator func_operator;
+ Form_pg_operator pgopform;
+ VacAttrStats *stats;
+
+ stats = &vacattrstats[i];
+ stats->attr = palloc(ATTRIBUTE_TUPLE_SIZE);
+ memmove(stats->attr, attr[((attnums) ? attnums[i] : i)], ATTRIBUTE_TUPLE_SIZE);
+ stats->best = stats->guess1 = stats->guess2 = 0;
+ stats->max = stats->min = 0;
+ stats->best_len = stats->guess1_len = stats->guess2_len = 0;
+ stats->max_len = stats->min_len = 0;
+ stats->initialized = false;
+ stats->best_cnt = stats->guess1_cnt = stats->guess1_hits = stats->guess2_hits = 0;
+ stats->max_cnt = stats->min_cnt = stats->null_cnt = stats->nonnull_cnt = 0;
+
+ func_operator = oper("=", stats->attr->atttypid, stats->attr->atttypid, true);
+ if (func_operator != NULL)
+ {
+ pgopform = (Form_pg_operator) GETSTRUCT(func_operator);
+ fmgr_info(pgopform->oprcode, &(stats->f_cmpeq));
+ }
+ else
+ stats->f_cmpeq.fn_addr = NULL;
+
+ func_operator = oper("<", stats->attr->atttypid, stats->attr->atttypid, true);
+ if (func_operator != NULL)
+ {
+ pgopform = (Form_pg_operator) GETSTRUCT(func_operator);
+ fmgr_info(pgopform->oprcode, &(stats->f_cmplt));
+ stats->op_cmplt = oprid(func_operator);
+ }
+ else
+ {
+ stats->f_cmplt.fn_addr = NULL;
+ stats->op_cmplt = InvalidOid;
+ }
+
+ func_operator = oper(">", stats->attr->atttypid, stats->attr->atttypid, true);
+ if (func_operator != NULL)
+ {
+ pgopform = (Form_pg_operator) GETSTRUCT(func_operator);
+ fmgr_info(pgopform->oprcode, &(stats->f_cmpgt));
+ }
+ else
+ stats->f_cmpgt.fn_addr = NULL;
+
+ typetuple = SearchSysCacheTuple(TYPEOID,
+ ObjectIdGetDatum(stats->attr->atttypid),
+ 0, 0, 0);
+ if (HeapTupleIsValid(typetuple))
+ {
+ stats->outfunc = ((Form_pg_type) GETSTRUCT(typetuple))->typoutput;
+ stats->typelem = ((Form_pg_type) GETSTRUCT(typetuple))->typelem;
+ }
+ else
+ {
+ stats->outfunc = InvalidOid;
+ stats->typelem = InvalidOid;
+ }
+ }
+ /* delete existing pg_statistic rows for relation */
+ del_stats(relid, ((attnums) ? attr_cnt : 0), attnums);
+
+ scan = heap_beginscan(onerel, false, SnapshotNow, 0, NULL);
+
+ while (HeapTupleIsValid(tuple = heap_getnext(scan, 0)))
+ attr_stats(onerel, attr_cnt, vacattrstats, tuple);
+
+ heap_endscan(scan);
+
+ heap_close(onerel, AccessShareLock);
+
+ /* update statistics in pg_class */
+ update_attstats(relid, attr_cnt, vacattrstats);
+
+ CommitTransactionCommand();
+}
+
+/*
+ * attr_stats() -- compute column statistics used by the optimzer
+ *
+ * We compute the column min, max, null and non-null counts.
+ * Plus we attempt to find the count of the value that occurs most
+ * frequently in each column. These figures are used to compute
+ * the selectivity of the column.
+ *
+ * We use a three-bucked cache to get the most frequent item.
+ * The 'guess' buckets count hits. A cache miss causes guess1
+ * to get the most hit 'guess' item in the most recent cycle, and
+ * the new item goes into guess2. Whenever the total count of hits
+ * of a 'guess' entry is larger than 'best', 'guess' becomes 'best'.
+ *
+ * This method works perfectly for columns with unique values, and columns
+ * with only two unique values, plus nulls.
+ *
+ * It becomes less perfect as the number of unique values increases and
+ * their distribution in the table becomes more random.
+ *
+ */
+static void
+attr_stats(Relation onerel, int attr_cnt, VacAttrStats *vacattrstats, HeapTuple tuple)
+{
+ int i;
+ TupleDesc tupDesc = onerel->rd_att;
+ Datum value;
+ bool isnull;
+
+ for (i = 0; i < attr_cnt; i++)
+ {
+ VacAttrStats *stats = &vacattrstats[i];
+ bool value_hit = true;
+
+#ifdef _DROP_COLUMN_HACK__
+ if (COLUMN_IS_DROPPED(stats->attr))
+ continue;
+#endif /* _DROP_COLUMN_HACK__ */
+ value = heap_getattr(tuple,
+ stats->attr->attnum, tupDesc, &isnull);
+
+ if (!VacAttrStatsEqValid(stats))
+ continue;
+
+ if (isnull)
+ stats->null_cnt++;
+ else
+ {
+ stats->nonnull_cnt++;
+ if (stats->initialized == false)
+ {
+ bucketcpy(stats->attr, value, &stats->best, &stats->best_len);
+ /* best_cnt gets incremented later */
+ bucketcpy(stats->attr, value, &stats->guess1, &stats->guess1_len);
+ stats->guess1_cnt = stats->guess1_hits = 1;
+ bucketcpy(stats->attr, value, &stats->guess2, &stats->guess2_len);
+ stats->guess2_hits = 1;
+ if (VacAttrStatsLtGtValid(stats))
+ {
+ bucketcpy(stats->attr, value, &stats->max, &stats->max_len);
+ bucketcpy(stats->attr, value, &stats->min, &stats->min_len);
+ }
+ stats->initialized = true;
+ }
+ if (VacAttrStatsLtGtValid(stats))
+ {
+ if ((*fmgr_faddr(&stats->f_cmplt)) (value, stats->min))
+ {
+ bucketcpy(stats->attr, value, &stats->min, &stats->min_len);
+ stats->min_cnt = 0;
+ }
+ if ((*fmgr_faddr(&stats->f_cmpgt)) (value, stats->max))
+ {
+ bucketcpy(stats->attr, value, &stats->max, &stats->max_len);
+ stats->max_cnt = 0;
+ }
+ if ((*fmgr_faddr(&stats->f_cmpeq)) (value, stats->min))
+ stats->min_cnt++;
+ else if ((*fmgr_faddr(&stats->f_cmpeq)) (value, stats->max))
+ stats->max_cnt++;
+ }
+ if ((*fmgr_faddr(&stats->f_cmpeq)) (value, stats->best))
+ stats->best_cnt++;
+ else if ((*fmgr_faddr(&stats->f_cmpeq)) (value, stats->guess1))
+ {
+ stats->guess1_cnt++;
+ stats->guess1_hits++;
+ }
+ else if ((*fmgr_faddr(&stats->f_cmpeq)) (value, stats->guess2))
+ stats->guess2_hits++;
+ else
+ value_hit = false;
+
+ if (stats->guess2_hits > stats->guess1_hits)
+ {
+ swapDatum(stats->guess1, stats->guess2);
+ swapInt(stats->guess1_len, stats->guess2_len);
+ swapLong(stats->guess1_hits, stats->guess2_hits);
+ stats->guess1_cnt = stats->guess1_hits;
+ }
+ if (stats->guess1_cnt > stats->best_cnt)
+ {
+ swapDatum(stats->best, stats->guess1);
+ swapInt(stats->best_len, stats->guess1_len);
+ swapLong(stats->best_cnt, stats->guess1_cnt);
+ stats->guess1_hits = 1;
+ stats->guess2_hits = 1;
+ }
+ if (!value_hit)
+ {
+ bucketcpy(stats->attr, value, &stats->guess2, &stats->guess2_len);
+ stats->guess1_hits = 1;
+ stats->guess2_hits = 1;
+ }
+ }
+ }
+ return;
+}
+
+/*
+ * bucketcpy() -- update pg_class statistics for one relation
+ *
+ */
+static void
+bucketcpy(Form_pg_attribute attr, Datum value, Datum *bucket, int *bucket_len)
+{
+ if (attr->attbyval && attr->attlen != -1)
+ *bucket = value;
+ else
+ {
+ int len = (attr->attlen != -1 ? attr->attlen : VARSIZE(value));
+
+ if (len > *bucket_len)
+ {
+ if (*bucket_len != 0)
+ pfree(DatumGetPointer(*bucket));
+ *bucket = PointerGetDatum(palloc(len));
+ *bucket_len = len;
+ }
+ memmove(DatumGetPointer(*bucket), DatumGetPointer(value), len);
+ }
+}
+
+
+/*
+ * update_attstats() -- update attribute statistics for one relation
+ *
+ * Updates of pg_attribute statistics are handled by over-write.
+ * for reasons described above.
+ *
+ * To keep things simple, we punt for pg_statistic, and don't try
+ * to compute or store rows for pg_statistic itself in pg_statistic.
+ * This could possibly be made to work, but it's not worth the trouble.
+ */
+static void
+update_attstats(Oid relid, int natts, VacAttrStats *vacattrstats)
+{
+ Relation ad,
+ sd;
+ HeapScanDesc scan;
+ HeapTuple atup,
+ stup;
+ ScanKeyData askey;
+ Form_pg_attribute attp;
+
+ ad = heap_openr(AttributeRelationName, RowExclusiveLock);
+ sd = heap_openr(StatisticRelationName, RowExclusiveLock);
+
+ /* Find pg_attribute rows for this relation */
+ ScanKeyEntryInitialize(&askey, 0, Anum_pg_attribute_attrelid,
+ F_INT4EQ, relid);
+
+ scan = heap_beginscan(ad, false, SnapshotNow, 1, &askey);
+
+ while (HeapTupleIsValid(atup = heap_getnext(scan, 0)))
+ {
+ int i;
+ VacAttrStats *stats;
+
+ attp = (Form_pg_attribute) GETSTRUCT(atup);
+ if (attp->attnum <= 0) /* skip system attributes for now */
+ continue;
+
+ for (i = 0; i < natts; i++)
+ {
+ if (attp->attnum == vacattrstats[i].attr->attnum)
+ break;
+ }
+ if (i >= natts)
+ continue; /* skip attr if no stats collected */
+ stats = &(vacattrstats[i]);
+
+ if (VacAttrStatsEqValid(stats))
+ {
+ float32data selratio; /* average ratio of rows selected
+ * for a random constant */
+
+ /* Compute disbursion */
+ if (stats->nonnull_cnt == 0 && stats->null_cnt == 0)
+ {
+
+ /*
+ * empty relation, so put a dummy value in
+ * attdisbursion
+ */
+ selratio = 0;
+ }
+ else if (stats->null_cnt <= 1 && stats->best_cnt == 1)
+ {
+ /*
+ * looks like we have a unique-key attribute --- flag
+ * this with special -1.0 flag value.
+ *
+ * The correct disbursion is 1.0/numberOfRows, but since
+ * the relation row count can get updated without
+ * recomputing disbursion, we want to store a
+ * "symbolic" value and figure 1.0/numberOfRows on the
+ * fly.
+ */
+ selratio = -1;
+ }
+ else
+ {
+ if (VacAttrStatsLtGtValid(stats) &&
+ stats->min_cnt + stats->max_cnt == stats->nonnull_cnt)
+ {
+
+ /*
+ * exact result when there are just 1 or 2
+ * values...
+ */
+ double min_cnt_d = stats->min_cnt,
+ max_cnt_d = stats->max_cnt,
+ null_cnt_d = stats->null_cnt;
+ double total = ((double) stats->nonnull_cnt) + null_cnt_d;
+
+ selratio = (min_cnt_d * min_cnt_d + max_cnt_d * max_cnt_d + null_cnt_d * null_cnt_d) / (total * total);
+ }
+ else
+ {
+ double most = (double) (stats->best_cnt > stats->null_cnt ? stats->best_cnt : stats->null_cnt);
+ double total = ((double) stats->nonnull_cnt) + ((double) stats->null_cnt);
+
+ /*
+ * we assume count of other values are 20% of best
+ * count in table
+ */
+ selratio = (most * most + 0.20 * most * (total - most)) / (total * total);
+ }
+ /* Make sure calculated values are in-range */
+ if (selratio < 0.0)
+ selratio = 0.0;
+ else if (selratio > 1.0)
+ selratio = 1.0;
+ }
+
+ /* overwrite the existing statistics in the tuple */
+ attp->attdisbursion = selratio;
+
+ /* invalidate the tuple in the cache and write the buffer */
+ RelationInvalidateHeapTuple(ad, atup);
+ WriteNoReleaseBuffer(scan->rs_cbuf);
+
+ /*
+ * Create pg_statistic tuples for the relation, if we have
+ * gathered the right data. del_stats() previously
+ * deleted all the pg_statistic tuples for the rel, so we
+ * just have to insert new ones here.
+ *
+ * Note vacuum_rel() has seen to it that we won't come here
+ * when vacuuming pg_statistic itself.
+ */
+ if (VacAttrStatsLtGtValid(stats) && stats->initialized)
+ {
+ float32data nullratio;
+ float32data bestratio;
+ FmgrInfo out_function;
+ char *out_string;
+ double best_cnt_d = stats->best_cnt,
+ null_cnt_d = stats->null_cnt,
+ nonnull_cnt_d = stats->nonnull_cnt; /* prevent overflow */
+ Datum values[Natts_pg_statistic];
+ char nulls[Natts_pg_statistic];
+
+ nullratio = null_cnt_d / (nonnull_cnt_d + null_cnt_d);
+ bestratio = best_cnt_d / (nonnull_cnt_d + null_cnt_d);
+
+ fmgr_info(stats->outfunc, &out_function);
+
+ for (i = 0; i < Natts_pg_statistic; ++i)
+ nulls[i] = ' ';
+
+ /* ----------------
+ * initialize values[]
+ * ----------------
+ */
+ i = 0;
+ values[i++] = (Datum) relid; /* starelid */
+ values[i++] = (Datum) attp->attnum; /* staattnum */
+ values[i++] = (Datum) stats->op_cmplt; /* staop */
+ /* hack: this code knows float4 is pass-by-ref */
+ values[i++] = PointerGetDatum(&nullratio); /* stanullfrac */
+ values[i++] = PointerGetDatum(&bestratio); /* stacommonfrac */
+ out_string = (*fmgr_faddr(&out_function)) (stats->best, stats->typelem, stats->attr->atttypmod);
+ values[i++] = PointerGetDatum(textin(out_string)); /* stacommonval */
+ pfree(out_string);
+ out_string = (*fmgr_faddr(&out_function)) (stats->min, stats->typelem, stats->attr->atttypmod);
+ values[i++] = PointerGetDatum(textin(out_string)); /* staloval */
+ pfree(out_string);
+ out_string = (char *) (*fmgr_faddr(&out_function)) (stats->max, stats->typelem, stats->attr->atttypmod);
+ values[i++] = PointerGetDatum(textin(out_string)); /* stahival */
+ pfree(out_string);
+
+ stup = heap_formtuple(sd->rd_att, values, nulls);
+
+ /* ----------------
+ * Watch out for oversize tuple, which can happen if
+ * all three of the saved data values are long.
+ * Our fallback strategy is just to not store the
+ * pg_statistic tuple at all in that case. (We could
+ * replace the values by NULLs and still store the
+ * numeric stats, but presently selfuncs.c couldn't
+ * do anything useful with that case anyway.)
+ *
+ * We could reduce the probability of overflow, but not
+ * prevent it, by storing the data values as compressed
+ * text; is that worth doing? The problem should go
+ * away whenever long tuples get implemented...
+ * ----------------
+ */
+ if (MAXALIGN(stup->t_len) <= MaxTupleSize)
+ {
+ /* OK, store tuple and update indexes too */
+ Relation irelations[Num_pg_statistic_indices];
+
+ heap_insert(sd, stup);
+ CatalogOpenIndices(Num_pg_statistic_indices, Name_pg_statistic_indices, irelations);
+ CatalogIndexInsert(irelations, Num_pg_statistic_indices, sd, stup);
+ CatalogCloseIndices(Num_pg_statistic_indices, irelations);
+ }
+
+ /* release allocated space */
+ pfree(DatumGetPointer(values[Anum_pg_statistic_stacommonval - 1]));
+ pfree(DatumGetPointer(values[Anum_pg_statistic_staloval - 1]));
+ pfree(DatumGetPointer(values[Anum_pg_statistic_stahival - 1]));
+ heap_freetuple(stup);
+ }
+ }
+ }
+ heap_endscan(scan);
+ /* close rels, but hold locks till upcoming commit */
+ heap_close(ad, NoLock);
+ heap_close(sd, NoLock);
+}
+
+/*
+ * del_stats() -- delete pg_statistic rows for a relation
+ *
+ * If a list of attribute numbers is given, only zap stats for those attrs.
+ */
+static void
+del_stats(Oid relid, int attcnt, int *attnums)
+{
+ Relation pgstatistic;
+ HeapScanDesc scan;
+ HeapTuple tuple;
+ ScanKeyData key;
+
+ pgstatistic = heap_openr(StatisticRelationName, RowExclusiveLock);
+
+ ScanKeyEntryInitialize(&key, 0x0, Anum_pg_statistic_starelid,
+ F_OIDEQ, ObjectIdGetDatum(relid));
+ scan = heap_beginscan(pgstatistic, false, SnapshotNow, 1, &key);
+
+ while (HeapTupleIsValid(tuple = heap_getnext(scan, 0)))
+ {
+ if (attcnt > 0)
+ {
+ Form_pg_statistic pgs = (Form_pg_statistic) GETSTRUCT(tuple);
+ int i;
+
+ for (i = 0; i < attcnt; i++)
+ {
+ if (pgs->staattnum == attnums[i] + 1)
+ break;
+ }
+ if (i >= attcnt)
+ continue; /* don't delete it */
+ }
+ heap_delete(pgstatistic, &tuple->t_self, NULL);
+ }
+
+ heap_endscan(scan);
+
+ /*
+ * Close rel, but *keep* lock; we will need to reacquire it later, so
+ * there's a possibility of deadlock against another VACUUM process if
+ * we let go now. Keeping the lock shouldn't delay any common
+ * operation other than an attempted VACUUM of pg_statistic itself.
+ */
+ heap_close(pgstatistic, NoLock);
+}
+
+
+
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