/*------------------------------------------------------------------------- * * vacuum.h * header file for postgres vacuum cleaner and statistics analyzer * * * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * src/include/commands/vacuum.h * *------------------------------------------------------------------------- */ #ifndef VACUUM_H #define VACUUM_H #include "access/htup.h" #include "catalog/pg_statistic.h" #include "catalog/pg_type.h" #include "nodes/parsenodes.h" #include "storage/buf.h" #include "storage/lock.h" #include "utils/relcache.h" /*---------- * ANALYZE builds one of these structs for each attribute (column) that is * to be analyzed. The struct and subsidiary data are in anl_context, * so they live until the end of the ANALYZE operation. * * The type-specific typanalyze function is passed a pointer to this struct * and must return TRUE to continue analysis, FALSE to skip analysis of this * column. In the TRUE case it must set the compute_stats and minrows fields, * and can optionally set extra_data to pass additional info to compute_stats. * minrows is its request for the minimum number of sample rows to be gathered * (but note this request might not be honored, eg if there are fewer rows * than that in the table). * * The compute_stats routine will be called after sample rows have been * gathered. Aside from this struct, it is passed: * fetchfunc: a function for accessing the column values from the * sample rows * samplerows: the number of sample tuples * totalrows: estimated total number of rows in relation * The fetchfunc may be called with rownum running from 0 to samplerows-1. * It returns a Datum and an isNull flag. * * compute_stats should set stats_valid TRUE if it is able to compute * any useful statistics. If it does, the remainder of the struct holds * the information to be stored in a pg_statistic row for the column. Be * careful to allocate any pointed-to data in anl_context, which will NOT * be CurrentMemoryContext when compute_stats is called. * * Note: for the moment, all comparisons done for statistical purposes * should use the database's default collation (DEFAULT_COLLATION_OID). * This might change in some future release. *---------- */ typedef struct VacAttrStats *VacAttrStatsP; typedef Datum (*AnalyzeAttrFetchFunc) (VacAttrStatsP stats, int rownum, bool *isNull); typedef void (*AnalyzeAttrComputeStatsFunc) (VacAttrStatsP stats, AnalyzeAttrFetchFunc fetchfunc, int samplerows, double totalrows); typedef struct VacAttrStats { /* * These fields are set up by the main ANALYZE code before invoking the * type-specific typanalyze function. * * Note: do not assume that the data being analyzed has the same datatype * shown in attr, ie do not trust attr->atttypid, attlen, etc. This is * because some index opclasses store a different type than the underlying * column/expression. Instead use attrtypid, attrtypmod, and attrtype for * information about the datatype being fed to the typanalyze function. */ Form_pg_attribute attr; /* copy of pg_attribute row for column */ Oid attrtypid; /* type of data being analyzed */ int32 attrtypmod; /* typmod of data being analyzed */ Form_pg_type attrtype; /* copy of pg_type row for attrtypid */ MemoryContext anl_context; /* where to save long-lived data */ /* * These fields must be filled in by the typanalyze routine, unless it * returns FALSE. */ AnalyzeAttrComputeStatsFunc compute_stats; /* function pointer */ int minrows; /* Minimum # of rows wanted for stats */ void *extra_data; /* for extra type-specific data */ /* * These fields are to be filled in by the compute_stats routine. (They * are initialized to zero when the struct is created.) */ bool stats_valid; float4 stanullfrac; /* fraction of entries that are NULL */ int4 stawidth; /* average width of column values */ float4 stadistinct; /* # distinct values */ int2 stakind[STATISTIC_NUM_SLOTS]; Oid staop[STATISTIC_NUM_SLOTS]; int numnumbers[STATISTIC_NUM_SLOTS]; float4 *stanumbers[STATISTIC_NUM_SLOTS]; int numvalues[STATISTIC_NUM_SLOTS]; Datum *stavalues[STATISTIC_NUM_SLOTS]; /* * These fields describe the stavalues[n] element types. They will be * initialized to match attrtypid, but a custom typanalyze function might * want to store an array of something other than the analyzed column's * elements. It should then overwrite these fields. */ Oid statypid[STATISTIC_NUM_SLOTS]; int2 statyplen[STATISTIC_NUM_SLOTS]; bool statypbyval[STATISTIC_NUM_SLOTS]; char statypalign[STATISTIC_NUM_SLOTS]; /* * These fields are private to the main ANALYZE code and should not be * looked at by type-specific functions. */ int tupattnum; /* attribute number within tuples */ HeapTuple *rows; /* access info for std fetch function */ TupleDesc tupDesc; Datum *exprvals; /* access info for index fetch function */ bool *exprnulls; int rowstride; } VacAttrStats; /* GUC parameters */ extern PGDLLIMPORT int default_statistics_target; /* PGDLLIMPORT for * PostGIS */ extern int vacuum_freeze_min_age; extern int vacuum_freeze_table_age; /* in commands/vacuum.c */ extern void vacuum(VacuumStmt *vacstmt, Oid relid, bool do_toast, BufferAccessStrategy bstrategy, bool for_wraparound, bool isTopLevel); extern void vac_open_indexes(Relation relation, LOCKMODE lockmode, int *nindexes, Relation **Irel); extern void vac_close_indexes(int nindexes, Relation *Irel, LOCKMODE lockmode); extern double vac_estimate_reltuples(Relation relation, bool is_analyze, BlockNumber total_pages, BlockNumber scanned_pages, double scanned_tuples); extern void vac_update_relstats(Relation relation, BlockNumber num_pages, double num_tuples, BlockNumber num_all_visible_pages, bool hasindex, TransactionId frozenxid, bool in_outer_xact); extern void vacuum_set_xid_limits(int freeze_min_age, int freeze_table_age, bool sharedRel, TransactionId *oldestXmin, TransactionId *freezeLimit, TransactionId *freezeTableLimit); extern void vac_update_datfrozenxid(void); extern void vacuum_delay_point(void); /* in commands/vacuumlazy.c */ extern void lazy_vacuum_rel(Relation onerel, VacuumStmt *vacstmt, BufferAccessStrategy bstrategy); /* in commands/analyze.c */ extern void analyze_rel(Oid relid, VacuumStmt *vacstmt, bool in_outer_xact, BufferAccessStrategy bstrategy); extern bool std_typanalyze(VacAttrStats *stats); extern double anl_random_fract(void); extern double anl_init_selection_state(int n); extern double anl_get_next_S(double t, int n, double *stateptr); #endif /* VACUUM_H */

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