src/include/commands/vacuum.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * vacuum.h
   4  *        header file for postgres vacuum cleaner and statistics analyzer
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * $PostgreSQL$
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 #ifndef VACUUM_H
  15 #define VACUUM_H
  16
  17 #include "access/htup.h"
  18 #include "catalog/pg_statistic.h"
  19 #include "catalog/pg_type.h"
  20 #include "nodes/parsenodes.h"
  21 #include "storage/buf.h"
  22 #include "storage/lock.h"
  23 #include "utils/relcache.h"
  24
  25
  26 /*----------
  27  * ANALYZE builds one of these structs for each attribute (column) that is
  28  * to be analyzed.      The struct and subsidiary data are in anl_context,
  29  * so they live until the end of the ANALYZE operation.
  30  *
  31  * The type-specific typanalyze function is passed a pointer to this struct
  32  * and must return TRUE to continue analysis, FALSE to skip analysis of this
  33  * column.      In the TRUE case it must set the compute_stats and minrows fields,
  34  * and can optionally set extra_data to pass additional info to compute_stats.
  35  * minrows is its request for the minimum number of sample rows to be gathered
  36  * (but note this request might not be honored, eg if there are fewer rows
  37  * than that in the table).
  38  *
  39  * The compute_stats routine will be called after sample rows have been
  40  * gathered.  Aside from this struct, it is passed:
  41  *              fetchfunc: a function for accessing the column values from the
  42  *                                 sample rows
  43  *              samplerows: the number of sample tuples
  44  *              totalrows: estimated total number of rows in relation
  45  * The fetchfunc may be called with rownum running from 0 to samplerows-1.
  46  * It returns a Datum and an isNull flag.
  47  *
  48  * compute_stats should set stats_valid TRUE if it is able to compute
  49  * any useful statistics.  If it does, the remainder of the struct holds
  50  * the information to be stored in a pg_statistic row for the column.  Be
  51  * careful to allocate any pointed-to data in anl_context, which will NOT
  52  * be CurrentMemoryContext when compute_stats is called.
  53  *----------
  54  */
  55 typedef struct VacAttrStats *VacAttrStatsP;
  56
  57 typedef Datum (*AnalyzeAttrFetchFunc) (VacAttrStatsP stats, int rownum,
  58                                                                                                    bool *isNull);
  59
  60 typedef struct VacAttrStats
  61 {
  62         /*
  63          * These fields are set up by the main ANALYZE code before invoking the
  64          * type-specific typanalyze function.
  65          */
  66         Form_pg_attribute attr;         /* copy of pg_attribute row for column */
  67         Form_pg_type attrtype;          /* copy of pg_type row for column */
  68         MemoryContext anl_context;      /* where to save long-lived data */
  69
  70         /*
  71          * These fields must be filled in by the typanalyze routine, unless it
  72          * returns FALSE.
  73          */
  74         void            (*compute_stats) (VacAttrStatsP stats,
  75                                                                                           AnalyzeAttrFetchFunc fetchfunc,
  76                                                                                           int samplerows,
  77                                                                                           double totalrows);
  78         int                     minrows;                /* Minimum # of rows wanted for stats */
  79         void       *extra_data;         /* for extra type-specific data */
  80
  81         /*
  82          * These fields are to be filled in by the compute_stats routine. (They
  83          * are initialized to zero when the struct is created.)
  84          */
  85         bool            stats_valid;
  86         float4          stanullfrac;    /* fraction of entries that are NULL */
  87         int4            stawidth;               /* average width of column values */
  88         float4          stadistinct;    /* # distinct values */
  89         int2            stakind[STATISTIC_NUM_SLOTS];
  90         Oid                     staop[STATISTIC_NUM_SLOTS];
  91         int                     numnumbers[STATISTIC_NUM_SLOTS];
  92         float4     *stanumbers[STATISTIC_NUM_SLOTS];
  93         int                     numvalues[STATISTIC_NUM_SLOTS];
  94         Datum      *stavalues[STATISTIC_NUM_SLOTS];
  95
  96         /*
  97          * These fields describe the stavalues[n] element types. They will
  98          * be initialized to be the same as the column's that's underlying the
  99          * slot, but a custom typanalyze function might want to store an array of
 100          * something other than the analyzed column's elements. It should then
 101          * overwrite these fields.
 102          */
 103         Oid                     statypid[STATISTIC_NUM_SLOTS];
 104         int2            statyplen[STATISTIC_NUM_SLOTS];
 105         bool            statypbyval[STATISTIC_NUM_SLOTS];
 106         char            statypalign[STATISTIC_NUM_SLOTS];
 107
 108         /*
 109          * These fields are private to the main ANALYZE code and should not be
 110          * looked at by type-specific functions.
 111          */
 112         int                     tupattnum;              /* attribute number within tuples */
 113         HeapTuple  *rows;                       /* access info for std fetch function */
 114         TupleDesc       tupDesc;
 115         Datum      *exprvals;           /* access info for index fetch function */
 116         bool       *exprnulls;
 117         int                     rowstride;
 118 } VacAttrStats;
 119
 120
 121 /* GUC parameters */
 122 extern PGDLLIMPORT int default_statistics_target;               /* PGDLLIMPORT for
 123                                                                                                                  * PostGIS */
 124 extern int      vacuum_freeze_min_age;
 125
 126
 127 /* in commands/vacuum.c */
 128 extern void vacuum(VacuumStmt *vacstmt, Oid relid, bool do_toast,
 129            BufferAccessStrategy bstrategy, bool for_wraparound, bool isTopLevel);
 130 extern void vac_open_indexes(Relation relation, LOCKMODE lockmode,
 131                                  int *nindexes, Relation **Irel);
 132 extern void vac_close_indexes(int nindexes, Relation *Irel, LOCKMODE lockmode);
 133 extern void vac_update_relstats(Oid relid,
 134                                         BlockNumber num_pages,
 135                                         double num_tuples,
 136                                         bool hasindex,
 137                                         TransactionId frozenxid);
 138 extern void vacuum_set_xid_limits(int freeze_min_age, bool sharedRel,
 139                                           TransactionId *oldestXmin,
 140                                           TransactionId *freezeLimit);
 141 extern void vac_update_datfrozenxid(void);
 142 extern bool vac_is_partial_index(Relation indrel);
 143 extern void vacuum_delay_point(void);
 144
 145 /* in commands/vacuumlazy.c */
 146 extern void lazy_vacuum_rel(Relation onerel, VacuumStmt *vacstmt,
 147                                 BufferAccessStrategy bstrategy);
 148
 149 /* in commands/analyze.c */
 150 extern void analyze_rel(Oid relid, VacuumStmt *vacstmt,
 151                         BufferAccessStrategy bstrategy);
 152
 153 #endif   /* VACUUM_H */