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7b504eb282
postgresql/src/include/utils/rel.h
Alvaro Herrera 7b504eb282 Implement multivariate n-distinct coefficients 
Add support for explicitly declared statistic objects (CREATE
STATISTICS), allowing collection of statistics on more complex
combinations that individual table columns.  Companion commands DROP
STATISTICS and ALTER STATISTICS ... OWNER TO / SET SCHEMA / RENAME are
added too.  All this DDL has been designed so that more statistic types
can be added later on, such as multivariate most-common-values and
multivariate histograms between columns of a single table, leaving room
for permitting columns on multiple tables, too, as well as expressions.

This commit only adds support for collection of n-distinct coefficient
on user-specified sets of columns in a single table.  This is useful to
estimate number of distinct groups in GROUP BY and DISTINCT clauses;
estimation errors there can cause over-allocation of memory in hashed
aggregates, for instance, so it's a worthwhile problem to solve.  A new
special pseudo-type pg_ndistinct is used.

(num-distinct estimation was deemed sufficiently useful by itself that
this is worthwhile even if no further statistic types are added
immediately; so much so that another version of essentially the same
functionality was submitted by Kyotaro Horiguchi:
https://postgr.es/m/20150828.173334.114731693.horiguchi.kyotaro@lab.ntt.co.jp
though this commit does not use that code.)

Author: Tomas Vondra.  Some code rework by Álvaro.
Reviewed-by: Dean Rasheed, David Rowley, Kyotaro Horiguchi, Jeff Janes,
    Ideriha Takeshi
Discussion: https://postgr.es/m/543AFA15.4080608@fuzzy.cz
    https://postgr.es/m/20170320190220.ixlaueanxegqd5gr@alvherre.pgsql
2017-03-24 14:06:10 -03:00

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/*-------------------------------------------------------------------------
*
* rel.h
* POSTGRES relation descriptor (a/k/a relcache entry) definitions.
*
*
* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/utils/rel.h
*
*-------------------------------------------------------------------------
*/
#ifndef REL_H
#define REL_H
#include "access/tupdesc.h"
#include "access/xlog.h"
#include "catalog/pg_class.h"
#include "catalog/pg_index.h"
#include "catalog/pg_publication.h"
#include "fmgr.h"
#include "nodes/bitmapset.h"
#include "rewrite/prs2lock.h"
#include "storage/block.h"
#include "storage/relfilenode.h"
#include "utils/relcache.h"
#include "utils/reltrigger.h"
/*
* LockRelId and LockInfo really belong to lmgr.h, but it's more convenient
* to declare them here so we can have a LockInfoData field in a Relation.
*/
typedef struct LockRelId
{
Oid relId; /* a relation identifier */
Oid dbId; /* a database identifier */
} LockRelId;
typedef struct LockInfoData
{
LockRelId lockRelId;
} LockInfoData;
typedef LockInfoData *LockInfo;
/*
* Information about the partition key of a relation
*/
typedef struct PartitionKeyData
{
char strategy; /* partitioning strategy */
int16 partnatts; /* number of columns in the partition key */
AttrNumber *partattrs; /* attribute numbers of columns in the
* partition key */
List *partexprs; /* list of expressions in the partitioning
* key, or NIL */
Oid *partopfamily; /* OIDs of operator families */
Oid *partopcintype; /* OIDs of opclass declared input data types */
FmgrInfo *partsupfunc; /* lookup info for support funcs */
/* Partitioning collation per attribute */
Oid *partcollation;
/* Type information per attribute */
Oid *parttypid;
int32 *parttypmod;
int16 *parttyplen;
bool *parttypbyval;
char *parttypalign;
Oid *parttypcoll;
} PartitionKeyData;
typedef struct PartitionKeyData *PartitionKey;
/*
* Here are the contents of a relation cache entry.
*/
typedef struct RelationData
{
RelFileNode rd_node; /* relation physical identifier */
/* use "struct" here to avoid needing to include smgr.h: */
struct SMgrRelationData *rd_smgr; /* cached file handle, or NULL */
int rd_refcnt; /* reference count */
BackendId rd_backend; /* owning backend id, if temporary relation */
bool rd_islocaltemp; /* rel is a temp rel of this session */
bool rd_isnailed; /* rel is nailed in cache */
bool rd_isvalid; /* relcache entry is valid */
char rd_indexvalid; /* state of rd_indexlist: 0 = not valid, 1 =
* valid, 2 = temporarily forced */
bool rd_statvalid; /* is rd_statlist valid? */
/*
* rd_createSubid is the ID of the highest subtransaction the rel has
* survived into; or zero if the rel was not created in the current top
* transaction. This can be now be relied on, whereas previously it could
* be "forgotten" in earlier releases. Likewise, rd_newRelfilenodeSubid is
* the ID of the highest subtransaction the relfilenode change has
* survived into, or zero if not changed in the current transaction (or we
* have forgotten changing it). rd_newRelfilenodeSubid can be forgotten
* when a relation has multiple new relfilenodes within a single
* transaction, with one of them occurring in a subsequently aborted
* subtransaction, e.g. BEGIN; TRUNCATE t; SAVEPOINT save; TRUNCATE t;
* ROLLBACK TO save; -- rd_newRelfilenode is now forgotten
*/
SubTransactionId rd_createSubid; /* rel was created in current xact */
SubTransactionId rd_newRelfilenodeSubid; /* new relfilenode assigned in
* current xact */
Form_pg_class rd_rel; /* RELATION tuple */
TupleDesc rd_att; /* tuple descriptor */
Oid rd_id; /* relation's object id */
LockInfoData rd_lockInfo; /* lock mgr's info for locking relation */
RuleLock *rd_rules; /* rewrite rules */
MemoryContext rd_rulescxt; /* private memory cxt for rd_rules, if any */
TriggerDesc *trigdesc; /* Trigger info, or NULL if rel has none */
/* use "struct" here to avoid needing to include rowsecurity.h: */
struct RowSecurityDesc *rd_rsdesc; /* row security policies, or NULL */
/* data managed by RelationGetFKeyList: */
List *rd_fkeylist; /* list of ForeignKeyCacheInfo (see below) */
bool rd_fkeyvalid; /* true if list has been computed */
MemoryContext rd_partkeycxt; /* private memory cxt for the below */
struct PartitionKeyData *rd_partkey; /* partition key, or NULL */
MemoryContext rd_pdcxt; /* private context for partdesc */
struct PartitionDescData *rd_partdesc; /* partitions, or NULL */
List *rd_partcheck; /* partition CHECK quals */
/* data managed by RelationGetIndexList: */
List *rd_indexlist; /* list of OIDs of indexes on relation */
Oid rd_oidindex; /* OID of unique index on OID, if any */
Oid rd_pkindex; /* OID of primary key, if any */
Oid rd_replidindex; /* OID of replica identity index, if any */
/* data managed by RelationGetStatExtList: */
List *rd_statlist; /* list of OIDs of extended stats */
/* data managed by RelationGetIndexAttrBitmap: */
Bitmapset *rd_indexattr; /* identifies columns used in indexes */
Bitmapset *rd_keyattr; /* cols that can be ref'd by foreign keys */
Bitmapset *rd_pkattr; /* cols included in primary key */
Bitmapset *rd_idattr; /* included in replica identity index */
PublicationActions *rd_pubactions; /* publication actions */
/*
* rd_options is set whenever rd_rel is loaded into the relcache entry.
* Note that you can NOT look into rd_rel for this data. NULL means "use
* defaults".
*/
bytea *rd_options; /* parsed pg_class.reloptions */
/* These are non-NULL only for an index relation: */
Form_pg_index rd_index; /* pg_index tuple describing this index */
/* use "struct" here to avoid needing to include htup.h: */
struct HeapTupleData *rd_indextuple; /* all of pg_index tuple */
/*
* index access support info (used only for an index relation)
*
* Note: only default support procs for each opclass are cached, namely
* those with lefttype and righttype equal to the opclass's opcintype. The
* arrays are indexed by support function number, which is a sufficient
* identifier given that restriction.
*
* Note: rd_amcache is available for index AMs to cache private data about
* an index. This must be just a cache since it may get reset at any time
* (in particular, it will get reset by a relcache inval message for the
* index). If used, it must point to a single memory chunk palloc'd in
* rd_indexcxt. A relcache reset will include freeing that chunk and
* setting rd_amcache = NULL.
*/
Oid rd_amhandler; /* OID of index AM's handler function */
MemoryContext rd_indexcxt; /* private memory cxt for this stuff */
/* use "struct" here to avoid needing to include amapi.h: */
struct IndexAmRoutine *rd_amroutine; /* index AM's API struct */
Oid *rd_opfamily; /* OIDs of op families for each index col */
Oid *rd_opcintype; /* OIDs of opclass declared input data types */
RegProcedure *rd_support; /* OIDs of support procedures */
FmgrInfo *rd_supportinfo; /* lookup info for support procedures */
int16 *rd_indoption; /* per-column AM-specific flags */
List *rd_indexprs; /* index expression trees, if any */
List *rd_indpred; /* index predicate tree, if any */
Oid *rd_exclops; /* OIDs of exclusion operators, if any */
Oid *rd_exclprocs; /* OIDs of exclusion ops' procs, if any */
uint16 *rd_exclstrats; /* exclusion ops' strategy numbers, if any */
void *rd_amcache; /* available for use by index AM */
Oid *rd_indcollation; /* OIDs of index collations */
/*
* foreign-table support
*
* rd_fdwroutine must point to a single memory chunk palloc'd in
* CacheMemoryContext. It will be freed and reset to NULL on a relcache
* reset.
*/
/* use "struct" here to avoid needing to include fdwapi.h: */
struct FdwRoutine *rd_fdwroutine; /* cached function pointers, or NULL */
/*
* Hack for CLUSTER, rewriting ALTER TABLE, etc: when writing a new
* version of a table, we need to make any toast pointers inserted into it
* have the existing toast table's OID, not the OID of the transient toast
* table. If rd_toastoid isn't InvalidOid, it is the OID to place in
* toast pointers inserted into this rel. (Note it's set on the new
* version of the main heap, not the toast table itself.) This also
* causes toast_save_datum() to try to preserve toast value OIDs.
*/
Oid rd_toastoid; /* Real TOAST table's OID, or InvalidOid */
/* use "struct" here to avoid needing to include pgstat.h: */
struct PgStat_TableStatus *pgstat_info; /* statistics collection area */
} RelationData;
/*
* ForeignKeyCacheInfo
* Information the relcache can cache about foreign key constraints
*
* This is basically just an image of relevant columns from pg_constraint.
* We make it a subclass of Node so that copyObject() can be used on a list
* of these, but we also ensure it is a "flat" object without substructure,
* so that list_free_deep() is sufficient to free such a list.
* The per-FK-column arrays can be fixed-size because we allow at most
* INDEX_MAX_KEYS columns in a foreign key constraint.
*
* Currently, we only cache fields of interest to the planner, but the
* set of fields could be expanded in future.
*/
typedef struct ForeignKeyCacheInfo
{
NodeTag type;
Oid conrelid; /* relation constrained by the foreign key */
Oid confrelid; /* relation referenced by the foreign key */
int nkeys; /* number of columns in the foreign key */
/* these arrays each have nkeys valid entries: */
AttrNumber conkey[INDEX_MAX_KEYS]; /* cols in referencing table */
AttrNumber confkey[INDEX_MAX_KEYS]; /* cols in referenced table */
Oid conpfeqop[INDEX_MAX_KEYS]; /* PK = FK operator OIDs */
} ForeignKeyCacheInfo;
/*
* StdRdOptions
* Standard contents of rd_options for heaps and generic indexes.
*
* RelationGetFillFactor() and RelationGetTargetPageFreeSpace() can only
* be applied to relations that use this format or a superset for
* private options data.
*/
/* autovacuum-related reloptions. */
typedef struct AutoVacOpts
{
bool enabled;
int vacuum_threshold;
int analyze_threshold;
int vacuum_cost_delay;
int vacuum_cost_limit;
int freeze_min_age;
int freeze_max_age;
int freeze_table_age;
int multixact_freeze_min_age;
int multixact_freeze_max_age;
int multixact_freeze_table_age;
int log_min_duration;
float8 vacuum_scale_factor;
float8 analyze_scale_factor;
} AutoVacOpts;
typedef struct StdRdOptions
{
int32 vl_len_; /* varlena header (do not touch directly!) */
int fillfactor; /* page fill factor in percent (0..100) */
AutoVacOpts autovacuum; /* autovacuum-related options */
bool user_catalog_table; /* use as an additional catalog
* relation */
int parallel_workers; /* max number of parallel workers */
} StdRdOptions;
#define HEAP_MIN_FILLFACTOR 10
#define HEAP_DEFAULT_FILLFACTOR 100
/*
* RelationGetFillFactor
* Returns the relation's fillfactor. Note multiple eval of argument!
*/
#define RelationGetFillFactor(relation, defaultff) \
((relation)->rd_options ? \
((StdRdOptions *) (relation)->rd_options)->fillfactor : (defaultff))
/*
* RelationGetTargetPageUsage
* Returns the relation's desired space usage per page in bytes.
*/
#define RelationGetTargetPageUsage(relation, defaultff) \
(BLCKSZ * RelationGetFillFactor(relation, defaultff) / 100)
/*
* RelationGetTargetPageFreeSpace
* Returns the relation's desired freespace per page in bytes.
*/
#define RelationGetTargetPageFreeSpace(relation, defaultff) \
(BLCKSZ * (100 - RelationGetFillFactor(relation, defaultff)) / 100)
/*
* RelationIsUsedAsCatalogTable
* Returns whether the relation should be treated as a catalog table
* from the pov of logical decoding. Note multiple eval of argument!
*/
#define RelationIsUsedAsCatalogTable(relation) \
((relation)->rd_options && \
((relation)->rd_rel->relkind == RELKIND_RELATION || \
(relation)->rd_rel->relkind == RELKIND_MATVIEW) ? \
((StdRdOptions *) (relation)->rd_options)->user_catalog_table : false)
/*
* RelationGetParallelWorkers
* Returns the relation's parallel_workers reloption setting.
* Note multiple eval of argument!
*/
#define RelationGetParallelWorkers(relation, defaultpw) \
((relation)->rd_options ? \
((StdRdOptions *) (relation)->rd_options)->parallel_workers : (defaultpw))
/*
* ViewOptions
* Contents of rd_options for views
*/
typedef struct ViewOptions
{
int32 vl_len_; /* varlena header (do not touch directly!) */
bool security_barrier;
int check_option_offset;
} ViewOptions;
/*
* RelationIsSecurityView
* Returns whether the relation is security view, or not. Note multiple
* eval of argument!
*/
#define RelationIsSecurityView(relation) \
((relation)->rd_options ? \
((ViewOptions *) (relation)->rd_options)->security_barrier : false)
/*
* RelationHasCheckOption
* Returns true if the relation is a view defined with either the local
* or the cascaded check option. Note multiple eval of argument!
*/
#define RelationHasCheckOption(relation) \
((relation)->rd_options && \
((ViewOptions *) (relation)->rd_options)->check_option_offset != 0)
/*
* RelationHasLocalCheckOption
* Returns true if the relation is a view defined with the local check
* option. Note multiple eval of argument!
*/
#define RelationHasLocalCheckOption(relation) \
((relation)->rd_options && \
((ViewOptions *) (relation)->rd_options)->check_option_offset != 0 ? \
strcmp((char *) (relation)->rd_options + \
((ViewOptions *) (relation)->rd_options)->check_option_offset, \
"local") == 0 : false)
/*
* RelationHasCascadedCheckOption
* Returns true if the relation is a view defined with the cascaded check
* option. Note multiple eval of argument!
*/
#define RelationHasCascadedCheckOption(relation) \
((relation)->rd_options && \
((ViewOptions *) (relation)->rd_options)->check_option_offset != 0 ? \
strcmp((char *) (relation)->rd_options + \
((ViewOptions *) (relation)->rd_options)->check_option_offset, \
"cascaded") == 0 : false)
/*
* RelationIsValid
* True iff relation descriptor is valid.
*/
#define RelationIsValid(relation) PointerIsValid(relation)
#define InvalidRelation ((Relation) NULL)
/*
* RelationHasReferenceCountZero
* True iff relation reference count is zero.
*
* Note:
* Assumes relation descriptor is valid.
*/
#define RelationHasReferenceCountZero(relation) \
((bool)((relation)->rd_refcnt == 0))
/*
* RelationGetForm
* Returns pg_class tuple for a relation.
*
* Note:
* Assumes relation descriptor is valid.
*/
#define RelationGetForm(relation) ((relation)->rd_rel)
/*
* RelationGetRelid
* Returns the OID of the relation
*/
#define RelationGetRelid(relation) ((relation)->rd_id)
/*
* RelationGetNumberOfAttributes
* Returns the number of attributes in a relation.
*/
#define RelationGetNumberOfAttributes(relation) ((relation)->rd_rel->relnatts)
/*
* RelationGetDescr
* Returns tuple descriptor for a relation.
*/
#define RelationGetDescr(relation) ((relation)->rd_att)
/*
* RelationGetRelationName
* Returns the rel's name.
*
* Note that the name is only unique within the containing namespace.
*/
#define RelationGetRelationName(relation) \
(NameStr((relation)->rd_rel->relname))
/*
* RelationGetNamespace
* Returns the rel's namespace OID.
*/
#define RelationGetNamespace(relation) \
((relation)->rd_rel->relnamespace)
/*
* RelationIsMapped
* True if the relation uses the relfilenode map.
*
* NB: this is only meaningful for relkinds that have storage, else it
* will misleadingly say "true".
*/
#define RelationIsMapped(relation) \
((relation)->rd_rel->relfilenode == InvalidOid)
/*
* RelationOpenSmgr
* Open the relation at the smgr level, if not already done.
*/
#define RelationOpenSmgr(relation) \
do { \
if ((relation)->rd_smgr == NULL) \
smgrsetowner(&((relation)->rd_smgr), smgropen((relation)->rd_node, (relation)->rd_backend)); \
} while (0)
/*
* RelationCloseSmgr
* Close the relation at the smgr level, if not already done.
*
* Note: smgrclose should unhook from owner pointer, hence the Assert.
*/
#define RelationCloseSmgr(relation) \
do { \
if ((relation)->rd_smgr != NULL) \
{ \
smgrclose((relation)->rd_smgr); \
Assert((relation)->rd_smgr == NULL); \
} \
} while (0)
/*
* RelationGetTargetBlock
* Fetch relation's current insertion target block.
*
* Returns InvalidBlockNumber if there is no current target block. Note
* that the target block status is discarded on any smgr-level invalidation.
*/
#define RelationGetTargetBlock(relation) \
( (relation)->rd_smgr != NULL ? (relation)->rd_smgr->smgr_targblock : InvalidBlockNumber )
/*
* RelationSetTargetBlock
* Set relation's current insertion target block.
*/
#define RelationSetTargetBlock(relation, targblock) \
do { \
RelationOpenSmgr(relation); \
(relation)->rd_smgr->smgr_targblock = (targblock); \
} while (0)
/*
* RelationNeedsWAL
* True if relation needs WAL.
*/
#define RelationNeedsWAL(relation) \
((relation)->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT)
/*
* RelationUsesLocalBuffers
* True if relation's pages are stored in local buffers.
*/
#define RelationUsesLocalBuffers(relation) \
((relation)->rd_rel->relpersistence == RELPERSISTENCE_TEMP)
/*
* RELATION_IS_LOCAL
* If a rel is either temp or newly created in the current transaction,
* it can be assumed to be accessible only to the current backend.
* This is typically used to decide that we can skip acquiring locks.
*
* Beware of multiple eval of argument
*/
#define RELATION_IS_LOCAL(relation) \
((relation)->rd_islocaltemp || \
(relation)->rd_createSubid != InvalidSubTransactionId)
/*
* RELATION_IS_OTHER_TEMP
* Test for a temporary relation that belongs to some other session.
*
* Beware of multiple eval of argument
*/
#define RELATION_IS_OTHER_TEMP(relation) \
((relation)->rd_rel->relpersistence == RELPERSISTENCE_TEMP && \
!(relation)->rd_islocaltemp)
/*
* RelationIsScannable
* Currently can only be false for a materialized view which has not been
* populated by its query. This is likely to get more complicated later,
* so use a macro which looks like a function.
*/
#define RelationIsScannable(relation) ((relation)->rd_rel->relispopulated)
/*
* RelationIsPopulated
* Currently, we don't physically distinguish the "populated" and
* "scannable" properties of matviews, but that may change later.
* Hence, use the appropriate one of these macros in code tests.
*/
#define RelationIsPopulated(relation) ((relation)->rd_rel->relispopulated)
/*
* RelationIsAccessibleInLogicalDecoding
* True if we need to log enough information to have access via
* decoding snapshot.
*/
#define RelationIsAccessibleInLogicalDecoding(relation) \
(XLogLogicalInfoActive() && \
RelationNeedsWAL(relation) && \
(IsCatalogRelation(relation) || RelationIsUsedAsCatalogTable(relation)))
/*
* RelationIsLogicallyLogged
* True if we need to log enough information to extract the data from the
* WAL stream.
*
* We don't log information for unlogged tables (since they don't WAL log
* anyway) and for system tables (their content is hard to make sense of, and
* it would complicate decoding slightly for little gain). Note that we *do*
* log information for user defined catalog tables since they presumably are
* interesting to the user...
*/
#define RelationIsLogicallyLogged(relation) \
(XLogLogicalInfoActive() && \
RelationNeedsWAL(relation) && \
!IsCatalogRelation(relation))
/*
* RelationGetPartitionKey
* Returns the PartitionKey of a relation
*/
#define RelationGetPartitionKey(relation) ((relation)->rd_partkey)
/*
* PartitionKey inquiry functions
*/
static inline int
get_partition_strategy(PartitionKey key)
{
return key->strategy;
}
static inline int
get_partition_natts(PartitionKey key)
{
return key->partnatts;
}
static inline List *
get_partition_exprs(PartitionKey key)
{
return key->partexprs;
}
/*
* PartitionKey inquiry functions - one column
*/
static inline int16
get_partition_col_attnum(PartitionKey key, int col)
{
return key->partattrs[col];
}
static inline Oid
get_partition_col_typid(PartitionKey key, int col)
{
return key->parttypid[col];
}
static inline int32
get_partition_col_typmod(PartitionKey key, int col)
{
return key->parttypmod[col];
}
/*
* RelationGetPartitionDesc
* Returns partition descriptor for a relation.
*/
#define RelationGetPartitionDesc(relation) ((relation)->rd_partdesc)
/* routines in utils/cache/relcache.c */
extern void RelationIncrementReferenceCount(Relation rel);
extern void RelationDecrementReferenceCount(Relation rel);
extern bool RelationHasUnloggedIndex(Relation rel);
extern List *RelationGetRepsetList(Relation rel);
#endif /* REL_H */
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