-.\" This is -*-nroff-*-
-.\" XXX standard disclaimer belongs here....
-.\" $Header: /cvsroot/pgsql/doc/src/sgml/catalogs.sgml,v 2.7 2000/07/17 03:04:40 tgl Exp $
-.TH "SYSTEM CATALOGS" INTRO 03/13/94 PostgreSQL PostgreSQL
-.SH "Section 7 - System Catalogs"
-.de LS
-.PP
-.if n .ta 5 +13 +13
-.if t .ta 0.5i +1.3i +1.3i
-.in 0
-.nf
-..
-.de LE
-.fi
-.in
-..
-.SH "DESCRIPTION"
-In this
-section we list each of the attributes of the system catalogs and
-define their meanings.
-.SH "CLASS/TYPE SYSTEM CATALOGS"
-These catalogs form the core of the extensibility system:
-.LS
- \fBname\fP \fBshared/local\fP \fBdescription\fP
- pg_aggregate local aggregate functions
- pg_am local access methods
- pg_amop local operators usable with specific access methods
- pg_amproc local procedures used with specific access methods
- pg_attribute local class attributes
- pg_class local classes
- pg_index local indices
- pg_inherits local class inheritance hierarchy
- pg_language local procedure implementation languages
- pg_opclass local operator classes
- pg_operator local query language operators
- pg_proc local procedures (functions)
- pg_type local data types
-.LE
-.SH "ENTITIES"
-These catalogs deal with identification of entities known throughout
-the site:
-.LS
- \fBname\fP \fBshared/local\fP \fBdescription\fP
- pg_database shared current databases
- pg_group shared user groups
- pg_shadow shared valid users
-.LE
-.SH "RULE SYSTEM CATALOGS"
-.LS
- \fBname\fP \fBshared/local\fP \fBdescription\fP
- pg_listener local processes waiting on alerters
- pg_prs2plans local instance system procedures
- pg_prs2rule local instance system rules
- pg_prs2stub local instance system ``stubs''
- pg_rewrite local rewrite system information
-.LE
-.SH "LARGE OBJECT CATALOGS"
-.PP
-These catalogs are specific to the Inversion file system and large
-objects in general:
-.LS
- \fBname\fP \fBshared/local\fP \fBdescription\fP
- pg_lobj local description of a large object
- pg_naming local Inversion name space mapping
- pg_platter local jukebox platter inventory
- pg_plmap local jukebox platter extent map
-.LE
-.SH "INTERNAL CATALOGS"
-.PP
-These catalogs are internal classes that are not stored as normal
-heaps and cannot be accessed through normal means (attempting to do so
-causes an error).
-.LS
- \fBname\fP \fBshared/local\fP \fBdescription\fP
- pg_log shared transaction commit/rollback log
- pg_magic shared magic constant
- pg_time shared commit/rollback times
- pg_variable shared special variable values
-.LE
-.PP
-There are several other classes defined with \*(lqpg_\*(rq names.
-Aside from those that end in \*(lqind\*(rq (secondary indices), these
-are all obsolete or otherwise deprecated.
-.SH "CLASS/TYPE SYSTEM CATALOGS"
-.PP
-The following catalogs relate to the class/type system.
-.nf M
-/*
- * aggregates
- *
- * see DEFINE AGGREGATE for an explanation of transition functions
- */
-pg_aggregate
- NameData aggname /* aggregate name (e.g., "count") */
- oid aggowner /* usesysid of creator */
- regproc aggtransfn /* transition function */
- regproc aggfinalfn /* final function */
- oid aggbasetype /* type of data on which aggregate
- operates */
- oid aggtranstype /* type of aggregate's transition
- (state) data */
- oid aggfinaltype /* type of aggregate's final result */
- text agginitval /* external format of initial state value */
-.fi
-.nf M
-pg_am
- NameData amname /* access method name */
- oid amowner /* usesysid of creator */
- int2 amstrategies /* total NUMBER of strategies by which
- we can traverse/search this AM */
- int2 amsupport /* total NUMBER of support functions
- that this AM uses */
- int2 amorderstrategy /* if this AM has a sort order, the
- * strategy number of the sort operator.
- * Zero if AM is not ordered.
- */
- regproc amgettuple /* "next valid tuple" function */
- regproc aminsert /* "insert this tuple" function */
- regproc amdelete /* "delete this tuple" function */
- regproc amgetattr /* - deprecated */
- regproc amsetlock /* - deprecated */
- regproc amsettid /* - deprecated */
- regproc amfreetuple /* - deprecated */
- regproc ambeginscan /* "start new scan" function */
- regproc amrescan /* "restart this scan" function */
- regproc amendscan /* "end this scan" function */
- regproc ammarkpos /* "mark current scan position"
- function */
- regproc amrestrpos /* "restore marked scan position"
- function */
- regproc amopen /* - deprecated */
- regproc amclose /* - deprecated */
- regproc ambuild /* "build new index" function */
- regproc amcreate /* - deprecated */
- regproc amdestroy /* - deprecated */
- regproc amcostestimate /* estimate cost of an indexscan */
-
-.fi
-.nf M
-pg_amop
- oid amopid /* access method with which this
- operator be used */
- oid amopclaid /* operator class with which this
- operator can be used */
- oid amopopr /* the operator */
- int2 amopstrategy /* traversal/search strategy number
- to which this operator applies */
-.fi
-.nf M
-pg_amproc
- oid amid /* access method with which this
- procedure is associated */
- oid amopclaid /* operator class with which this
- operator can be used */
- oid amproc /* the procedure */
- int2 amprocnum /* support function number to which
- this operator applies */
-.fi
-.nf M
-pg_class
- NameData relname /* class name */
- oid relowner /* usesysid of owner */
- oid relam /* access method */
- int4 relpages /* # of 8KB pages */
- int4 reltuples /* # of instances */
- abstime relexpires /* time after which instances are
- deleted from non-archival storage */
- reltime relpreserved /* timespan after which instances are
- deleted from non-archival storage */
- bool relhasindex /* does the class have a secondary
- index? */
- bool relisshared /* is the class shared or local? */
- char relkind /* type of relation:
- i=index
- r=relation (heap)
- s=special
- u=uncatalogued (temporary) */
- char relarch /* archive mode:
- h=heavy
- l=light
- n=none */
- int2 relnatts /* current # of non-system
- attributes */
- int2 relsmgr /* storage manager:
- 0=magnetic disk
- 1=sony WORM jukebox
- 2=main memory */
- int2vector relkey /* - unused */
- oidvector relkeyop /* - unused */
- bool relhassubclass /* does the class have a subclass?
- */
- aclitem relacl[1] /* access control lists */
-.fi
-.nf M
-pg_attribute
- oid attrelid /* class containing this attribute */
- NameData attname /* attribute name */
- oid atttypid /* attribute type */
- oid attdefrel /* - deprecated */
- int4 attnvals /* - deprecated */
- oid atttyparg /* - deprecated */
- int2 attlen /* attribute length, in bytes
- -1=variable */
- int2 attnum /* attribute number
- >0=user attribute
- <0=system attribute */
- int2 attbound /* - deprecated */
- bool attbyval /* type passed by value? */
- bool attcanindex /* - deprecated */
- oid attproc /* - deprecated */
- int4 attnelems /* # of array dimensions */
- int4 attcacheoff /* cached offset into tuple */
- bool attisset /* is attribute set-valued? */
-.fi
-.nf M
-pg_inherits
- oid inhrel /* child class */
- oid inhparent /* parent class */
- int4 inhseqno /* - deprecated */
-.fi
-.nf M
- oid indexrelid /* oid of secondary index class */
- oid indrelid /* oid of indexed heap class */
- oid indproc /* function to compute index key from
- attribute(s) in heap
- 0=not a functional index */
- int2vector indkey /* attribute numbers of key
- attribute(s) */
- oidvector indclass /* opclass of each key */
- bool indisclustered /* is the index clustered?
- - unused */
- bool indisarchived /* is the index archival?
- - unused */
- text indpred /* query plan for partial index
- predicate */
-.fi
-.nf M
-pg_type
- NameData typname /* type name */
- oid typowner /* usesysid of owner */
- int2 typlen /* length in internal form
- -1=variable-length */
- int2 typprtlen /* length in external form */
- bool typbyval /* type passed by value? */
- char typtype /* kind of type:
- c=catalog (composite)
- b=base */
- bool typisdefined /* defined or still a shell? */
- char typdelim /* delimiter for array external form */
- oid typrelid /* class (if composite) */
- oid typelem /* type of each array element */
- regproc typinput /* external-internal conversion
- function */
- regproc typoutput /* internal-external conversion
- function */
- regproc typreceive /* client-server conversion function */
- regproc typsend /* server-client conversion function */
- text typdefault /* default value */
-.fi
-.nf M
-pg_operator
- NameData oprname /* operator name */
- oid oprowner /* usesysid of owner */
- int2 oprprec /* - deprecated */
- char oprkind /* kind of operator:
- b=binary
- l=left unary
- r=right unary */
- bool oprisleft /* is operator left/right associative? */
- bool oprcanhash /* is operator usable for hashjoin? */
- oid oprleft /* left operand type */
- oid oprright /* right operand type */
- oid oprresult /* result type */
- oid oprcom /* commutator operator */
- oid oprnegate /* negator operator */
- oid oprlsortop /* sort operator for left operand */
- oid oprrsortop /* sort operator for right operand */
- regproc oprcode /* function implementing this operator */
- regproc oprrest /* function to calculate operator
- restriction selectivity */
- regproc oprjoin /* function to calculate operator
- join selectivity */
-.fi
-.nf M
-pg_opclass
- NameData opcname /* operator class name */
-.fi
-.nf M
-pg_proc
- NameData proname /* function name */
- oid proowner /* usesysid of owner */
- oid prolang /* function implementation language */
- bool proisinh /* - deprecated */
- bool proistrusted /* run in server or untrusted function
- process? */
- bool proiscachable /* can the function return values be
- cached? */
- int2 pronargs /* # of arguments */
- bool proretset /* does the function return a set?
- - unused */
- oid prorettype /* return type */
- oidvector proargtypes /* argument types */
- int4 probyte_pct /* % of argument size (in bytes) that
- needs to be examined in order to
- compute the function */
- int4 properbyte_cpu /* sensitivity of the function's
- running time to the size of its
- inputs */
- int4 propercall_cpu /* overhead of the function's
- invocation (regardless of input
- size) */
- int4 prooutin_ratio /* size of the function's output as a
- percentage of the size of the input */
- text prosrc /* function definition:
- INTERNAL function: actual C name of function
- C function: currently, this field is unused
- SQL function: text of query(s)
- PL function: text in procedural language */
- bytea probin /* path to object file (C functions only) */
-.fi
-.nf M
-pg_language
- NameData lanname /* language name */
- text lancompiler /* - deprecated */
-.fi
-.SH "ENTITIES"
-.nf M
-pg_database
- NameData datname /* database name */
- oid datdba /* usesysid of database administrator */
- text datpath /* directory of database under
- $PGDATA */
-.fi
-.nf M
-pg_group
- NameData groname /* group name */
- int2 grosysid /* group's UNIX group id */
- int2 grolist[1] /* list of usesysids of group members */
-.fi
-.nf M
-pg_shadow
- NameData usename /* user's name */
- int2 usesysid /* user's UNIX user id */
- bool usecreatedb /* can user create databases? */
- bool usetrace /* can user set trace flags? */
- bool usesuper /* can user be POSTGRES superuser? */
- bool usecatupd /* can user update catalogs? */
-.fi
-.SH "RULE SYSTEM CATALOGS"
-.nf M
-pg_listener
- NameData relname /* class for which asynchronous
- notification is desired */
- int4 listenerpid /* process id of server corresponding
- to a frontend program waiting for
- asynchronous notification */
- int4 notification /* whether an event notification for
- this process id still pending */
-
-.fi
-.nf M
-pg_prs2rule
- NameData prs2name /* rule name */
- char prs2eventtype /* rule event type:
- R=retrieve
- U=update (replace)
- A=append
- D=delete */
- oid prs2eventrel /* class to which event applies */
- int2 prs2eventattr /* attribute to which event applies */
- float8 necessary /* - deprecated */
- float8 sufficient /* - deprecated */
- text prs2text /* text of original rule definition */
-.fi
-.nf M
-pg_prs2plans
- oid prs2ruleid /* prs2rule instance for which this
- plan is used */
- int2 prs2planno /* plan number (one rule may invoke
- multiple plans) */
- text prs2code /* external representation of the plan */
-.fi
-.nf M
-pg_prs2stub
- oid prs2relid /* class to which this rule applies */
- bool prs2islast /* is this the last stub fragment? */
- int4 prs2no /* stub fragment number */
- stub prs2stub /* stub fragment */
-.fi
-.nf M
-pg_rewrite
- NameData rulename /* rule name */
- char ev_type /* event type:
- RETRIEVE, REPLACE, APPEND, DELETE
- codes are parser-dependent (!?) */
- oid ev_class /* class to which this rule applies */
- int2 ev_attr /* attribute to which this rule applies */
- bool is_instead /* is this an "instead" rule? */
- text ev_qual /* qualification with which to modify
- (rewrite) the plan that triggered this
- rule */
- text action /* parse tree of action */
-.fi
-.SH "LARGE OBJECT CATALOGS"
-.nf M
-pg_lobj
- oid ourid /* 'ourid' from pg_naming that
- identifies this object in the
- Inversion file system namespace */
- int4 objtype /* storage type code:
- 0=Inversion
- 1=Unix
- 2=External
- 3=Jaquith */
- bytea object_descripto/* opaque object-handle structure */
-.fi
-.nf M
-pg_naming
- NameData filename /* filename component */
- oid ourid /* random oid used to identify this
- instance in other instances (can't
- use the actual oid for obscure
- reasons */
- oid parentid /* pg_naming instance of parent
- Inversion file system directory */
-.fi
-.nf M
-pg_platter
- NameData plname /* platter name */
- int4 plstart /* the highest OCCUPIED extent */
-.fi
-.nf M
-pg_plmap
- oid plid /* platter (in pg_platter) on which
- this extent (of blocks) resides */
- oid pldbid /* database of the class to which this
- extent (of blocks) belongs */
- oid plrelid /* class to which this extend (of
- blocks) belongs */
- int4 plblkno /* starting block number within the
- class */
- int4 ploffset /* offset within the platter at which
- this extent begins */
- int4 plextentsz /* length of this extent */
-.fi
+
+
+
+
System Catalogs
+
+
+
Overview
+
+ The system catalogs are the place where a relational database
+ management system stores schema metadata, such as information about
+ tables and columns, and internal bookkeeping information.
+
PostgreSQL's system catalogs are regular
+ tables. You can drop and recreate the tables, add columns, insert
+ and update values, and severely mess up your system that way.
+ Normally one never has to change the system catalogs by hand, there
+ are always SQL commands to do that. (For example, CREATE
+ DATABASE inserts a row into the
+ pg_database catalog -- and actually
+ creates the database on disk.) There are some exceptions for
+ esoteric operations, such as adding index access methods.
+
+
+
+
System Catalogs
+
+
+
+ |
+ Catalog Name
+ Purpose
+
+
+
+
+ |
+ pg_aggregate
+ aggregate functions
+
+
+ |
+ pg_am
+ index access methods
+
+
+ |
+ pg_amop
+ access method operators
+
+
+ |
+ pg_amproc
+ access method support procedures
+
+
+ |
+ pg_attrdef
+ column default values
+
+
+ |
+ pg_attribute
+ table columns (attributes, fields)
+
+
+ |
+ pg_class
+ tables, indexes, sequences (relations
)
+
+
+ |
+ pg_database
+ databases
+
+
+ |
+ pg_description
+ descriptions or comments on database objects
+
+
+ |
+ pg_group
+ user groups
+
+
+ |
+ pg_index
+ additional index information
+
+
+ |
+ pg_inheritproc
+ (not used)
+
+
+ |
+ pg_inherits
+ table inheritance hierarchy
+
+
+ |
+ pg_ipl
+ (not used)
+
+
+ |
+ pg_language
+ languages for writing functions
+
+
+ |
+ pg_largeobject
+ large objects
+
+
+ |
+ pg_listener
+ asynchronous notification
+
+
+ |
+ pg_opclass
+ index access method operator classes
+
+
+ |
+ pg_operator
+ operators
+
+
+ |
+ pg_proc
+ functions and procedures
+
+
+ |
+ pg_relcheck
+ check constraints
+
+
+ |
+ pg_rewrite
+ query rewriter rules
+
+
+ |
+ pg_shadow
+ database users
+
+
+ |
+ pg_statistic
+ optimizer statistics
+
+
+ |
+ pg_trigger
+ triggers
+
+
+ |
+ pg_type
+ data types
+
+
+
+
+
+ More detailed documentation of most catalogs follow below. The
+ catalogs that relate to index access methods are explained in the
+ Programmer's Guide. Some catalogs don't
+ have any documentation, yet.
+
+
+
+
+
+
+
pg_aggregate
+
+ pg_aggregate stores information about
+ aggregate functions. An aggregate function is a function that
+ operates on a set of values (typically one column from each the row
+ that matches a query condition) and returns a single value computed
+ from all these values. Typical aggregate functions are
+ sum, count, and
+ max.
+
+
+
+
pg_aggregate Columns
+
+
+
+ |
+ Name
+ Type
+ References
+ Description
+
+
+
+ |
+ aggname
+ name
+
+ Name of the aggregate function
+
+ |
+ aggowner
+ int4
+ pg_shadow.usesysid
+ Owner (creator) of the aggregate function
+
+ |
+ aggtransfn
+ regproc (function)
+
+ Transition function
+
+ |
+ aggfinalfn
+ regproc (function)
+
+ Final function
+
+ |
+ aggbasetype
+ oid
+ pg_type.oid
+ The type on which this function operates when invoked from SQL
+
+ |
+ aggtranstype
+ oid
+ pg_type.oid
+ The type of the aggregate function's internal transition (state) data
+
+ |
+ aggfinaltype
+ oid
+ pg_type.oid
+ The type of the result
+
+ |
+ agginitval
+ text
+
+
+ The initial value of the transition state. This is a text
+ field which will be cast to the type of aggtranstype.
+
+
+
+
+
+
+ New aggregate functions are registered with the CREATE
+ AGGREGATE command. See the Programmer's
+ Guide for more information about writing aggregate
+ functions and the meaning of the transition functions, etc.
+
+
+ An aggregate function is identified through name
+ and argument type. Hence aggname and aggname
+ are the composite primary key.
+
+
+
+
+
+
+
pg_attrdef
+
+ This catalog stores column default values. The main information
+ about columns is stored in pg_attribute
+ (see below). Only columns that explicitly specify a default value
+ (when the table is created or the column is added) will have an
+ entry here.
+
+
+
+
pg_attrdef Columns
+
+
+
+ |
+ Name
+ Type
+ References
+ Description
+
+
+
+
+ |
+ adrelid
+ oid
+ pg_class.oid
+ The table this column belongs to
+
+
+ |
+ adnum
+ int2
+
+
+ The number of the column; see
+ pg_attribute.pg_attnum
+
+
+
+ |
+ adbin
+ text
+
+ An internal representation of the column default value
+
+
+ |
+ adsrc
+ text
+
+ A human-readable representation of the default value
+
+
+
+
+
+
+
+
+
+
pg_attribute
+
+ pg_attribute stores information about
+ table columns. There will be exactly one
+ pg_attribute row for every column in every
+ table in the database. (There will also be attribute entries for
+ indexes and other objects. See pg_class.)
+
+
+ The term attribute is equivalent to column and is used for
+ historical reasons.
+
+
+
+
pg_attribute Columns
+
+
+
+ |
+ Name
+ Type
+ References
+ Description
+
+
+
+
+ |
+ attrelid
+ oid
+ pg_class.oid
+ The table this column belongs to
+
+
+ |
+ attname
+ name
+
+ Column name
+
+
+ |
+ atttypid
+ oid
+ pg_type.oid
+ The data type of this column
+
+
+ |
+ attdispersion
+ float4
+
+
+ attdispersion is the dispersion
+ statistic of the column (0.0 to 1.0), or zero if the statistic
+ has not been calculated, or -1.0 if VACUUM
+ found that the column contains no duplicate entries (in which
+ case the dispersion should be taken as
+ 1.0/numberOfRows for the current table size).
+ The -1.0 hack is useful because the number of rows may be
+ updated more often than
+ attdispersion is. We assume that the
+ column will retain its no-duplicate-entry property.
+
+
+
+ |
+ attlen
+ int2
+
+
+ This is a copy of the
+ pg_type.typlen
+ for this column's type.
+
+
+
+ |
+ attnum
+ int2
+
+
+ The number of the column. Ordinary columns are numbered from 1
+ up. System columns, such as oid,
+ have (arbitrary) negative numbers.
+
+
+
+ |
+ attnelems
+ int4
+
+ Number of dimensions, if the column is an array
+
+
+ |
+ attcacheoff
+ int4
+
+
+ Always -1 in storage, but when loaded into a tuple descriptor
+ in memory this may be updated cache the offset of the attribute
+ within the tuple.
+
+
+
+ |
+ atttypmod
+ int4
+
+
+ atttypmod records type-specific data
+ supplied at table creation time (for example, the maximum
+ length of a varchar column). It is passed to
+ type-specific input and output functions as the third
+ argument. The value will generally be -1 for types that do not
+ need typmod.
+
+
+
+ |
+ attbyval
+ bool
+
+
+ A copy of
+ pg_type.typbyval
+ of this column's type
+
+
+
+ |
+ attstorage
+ char
+
+
+ A copy of
+ pg_type.typstorage
+ of this column's type
+
+
+
+ |
+ attisset
+ bool
+
+
+ If true, this attribute is a set. In that case, what is really
+ stored in the attribute is the OID of a tuple in the
+ pg_proc catalog. The
+ pg_proc tuple contains the query
+ string which defines this set - i.e., the query to run to get
+ the set. So the atttypid (see
+ above) refers to the type returned by this query, but the
+ actual length of this attribute is the length (size) of an
+ oid. --- At least this is the theory. All this
+ is probably quite broken these days.
+
+
+
+ |
+ attalign
+ char
+
+
+ A copy of
+ pg_type.typalign
+ of this column's type
+
+
+
+ |
+ attnotnull
+ bool
+
+
+ This represents a NOT NULL constraint. It is possible to
+ change this field to enable or disable the constraint.
+
+
+
+ |
+ atthasdef
+ bool
+
+
+ This column has a default value, in which case there will be a
+ corresponding entry in the pg_attrdef
+ catalog that actually defines the value.
+
+
+
+
+
+
+
+
+
+
+
pg_class
+
+ pg_class catalogues tables and mostly
+ everything else that has columns or is otherwise similar to a
+ table. This includes indexes (but see
+ pg_index), sequences, views, and some
+ kinds of special relation kinds. Below, when we mean all of these
+ kinds of objects we speak of relations
. Not all
+ fields are meaningful for all relation types.
+
+
+
+
pg_class Columns
+
+
+
+ |
+ Name
+ Type
+ References
+ Description
+
+
+
+
+ |
+ relname
+ name
+
+ Name of the table, index, view, etc.
+
+
+ |
+ reltype
+ oid
+ pg_type.oid
+
+ The data type that corresponds to this table (not functional,
+ only set for system tables)
+
+
+
+ |
+ relowner
+ int4
+ pg_shadow.usesysid
+ Owner of the relation
+
+
+ |
+ relam
+ oid
+ pg_am.oid
+ If this is an index, the access method used (btree, hash, etc.)
+
+
+ |
+ relfilenode
+ oid
+
+ Name of the on-disk file of this relation
+
+
+ |
+ relpages
+ int4
+
+
+ Size of the on-disk representation of this table in pages (size
+ BLCKSZ). This is only an approximate value
+ which is calculated during vacuum.
+
+
+
+ |
+ reltuples
+ int4
+
+
+ Number of tuples in the table. This is only an estimate used
+ by the planner, updated by VACUUM.
+
+
+
+ |
+ reltoastrelid
+ oid
+ pg_class.oid
+
+ Oid of the TOAST table associated with this table, 0 if none.
+ The TOAST table stores large attributes out of
+ line in a secondary table.
+
+
+
+ |
+ reltoastidxid
+ oid
+ pg_class.oid
+ Oid of the index on the TOAST table for this table, 0 if none
+
+
+ |
+ relhasindex
+ bool
+
+ True if this is a table and it has at least one index
+
+
+ |
+ relisshared
+ bool
+
+ XXX (This is not what it seems to be.)
+
+
+ |
+ relkind
+ char
+
+
+ 'r' = ordinary table, 'i' = index, 'S' = sequence, 'v' = view,
+ 's' = special, 't' = secondary TOAST table
+
+
+
+ |
+ relnatts
+ int2
+
+
+ Number of columns in the relation, besides system columns.
+ There must be this many corresponding entries in
+ pg_attribute. See also
+ pg_attribute.attnum.
+
+
+
+ |
+ relchecks
+ int2
+
+
+ Number of check constraints on the table; see
+ pg_relcheck catalog
+
+
+
+ |
+ reltriggers
+ int2
+
+
+ Number of triggers on the table; see
+ pg_trigger catalog
+
+
+
+ |
+ relukeys
+ int2
+
+ unused (Not the number of unique keys or something.)
+
+
+ |
+ relfkeys
+ int2
+
+ Number foreign keys on the table
+
+
+ |
+ relhaspkey
+ bool
+
+
+ unused (No, this does not say whether the table has a primary
+ key. It's really unused.)
+
+
+
+ |
+ relhasrules
+ bool
+
+ Table has rules
+
+
+ |
+ relhassubclass
+ bool
+
+ At least one table inherits this one
+
+
+ |
+ relacl
+ aclitem[]
+
+
+ Access permissions. See the descriptions of
+ GRANT and REVOKE for
+ details.
+
+
+
+
+
+
+
+
+
+
pg_database
+
+ The pg_database catalog stores information
+ about the available databases. The
+ pg_database table is shared between all
+ databases of a cluster. Databases are created with the
+ CREATE DATABASE. Consult the
+ Administrator's Guide for details about the
+ meaning of some of the parameters.
+
+
+
+
pg_database Columns
+
+
+
+ |
+ Name
+ Type
+ References
+ Description
+
+
+
+
+ |
+ datname
+ name
+
+ Database name
+
+
+ |
+ datdba
+ int4
+ pg_shadow.usesysid
+ Owner of the database, initially who created it
+
+
+ |
+ encoding
+ int4
+
+ Character/multibyte encoding for this database
+
+
+ |
+ datistemplate
+ bool
+
+
+ If true then this database can be used in the
+ TEMPLATE
clause of CREATE
+ DATABASE to create the new database as a clone of
+ this one.
+
+
+
+ |
+ datallowconn
+ bool
+
+
+ If false then no one can connect to this database. This is
+ used to protect the template0 database from being altered.
+
+
+
+ |
+ datlastsysoid
+ oid
+
+
+ Last oid in existence after the database was created; useful
+ particularly to
pg_dump+
+
+
+ |
+ datpath
+ text
+
+
+ If the database is stored at an alternative location then this
+ records the location. It's either an environment variable name
+ or an absolute path, depending how it was entered.
+
+
+
+
+
+
+
+
+
+
pg_description
+
+ The pg_description table can store an optional description or
+ comment for each database object. Descriptions can be manipulated
+ with the COMMENT command. Client applications
+ can view the descriptions by joining with this table. Many builtin
+ system objects have comments associated with them that are shown by
+
+
+
+
pg_description Columns
+
+
+
+ |
+ Name
+ Type
+ References
+ Description
+
+
+
+
+ |
+ objoid
+ oid
+ any oid attribute
+ The oid of the object this description pertains to
+
+
+ |
+ description
+ text
+
+ Arbitrary text that serves as the description of this object.
+
+
+
+
+
+
+
+
+
+
pg_group
+
+ This catalog defines groups and stores what users belong to what
+ groups. Groups are created with the CREATE
+ GROUP command. Consult the Administrator's
+ Guide for information about user permission management.
+
+
+
+
pg_group Columns
+
+
+
+ |
+ Name
+ Type
+ References
+ Description
+
+
+
+
+ |
+ groname
+ name
+
+ Name of the group
+
+
+ |
+ grosysid
+ int4
+
+ An arbitrary number to identify this group
+
+
+ |
+ grolist
+ int4[]
+ pg_shadow.usesysid
+ An array containing the ids of the users in this group
+
+
+
+
+
+
+
+
+
+
pg_index
+
+ pg_index contains part of the information
+ about indexes. The rest is mostly in
+ pg_class.
+
+
+
+
pg_index Columns
+
+
+
+ |
+ Name
+ Type
+ References
+ Description
+
+
+
+
+ |
+ indexrelid
+ oid
+ pg_class.oid
+ The oid of the pg_class entry for this index
+
+
+ |
+ indrelid
+ oid
+ pg_class.oid
+ The oid of the pg_class entry for the table this index is for
+
+
+ |
+ indproc
+ oid
+ pg_proc.oid
+ The registered procedure if this is a functional index
+
+
+ |
+ indkey
+ int2vector
+ pg_attribute.attnum
+
+ This is an vector (array) of up to
+ INDEX_MAX_KEYS values that indicate which
+ table columns this index pertains to. For example a value of
+ 1 3 would mean that the first and the third
+ column make up the index key.
+
+
+
+ |
+ indclass
+ oidvector
+ pg_opclass.oid
+
+ For each column in the index key this contains a reference to
+ the operator class
to use. See
+ pg_opclass for details.
+
+
+
+ |
+ indisclustered
+ bool
+
+ unused
+
+
+ |
+ indislossy
+ bool
+
+ ???
+
+
+ |
+ indisunique
+ bool
+
+ If true, this is a unique index.
+
+
+ |
+ indisprimary
+ bool
+
+ If true, this index is a unique index that represents the primary key of the table.
+
+
+ |
+ indreference
+ oid
+
+ unused
+
+
+ |
+ indpred
+ text
+
+ Query plan for partial index predicate (not functional)
+
+
+
+
+
+
+
+
+
+
pg_inherits
+
+ This catalog records information about table inheritance hierarchies.
+
+
+
+
pg_inherits Columns
+
+
+
+ |
+ Name
+ Type
+ References
+ Description
+
+
+
+
+ |
+ inhrelid
+ oid
+ pg_class.oid
+
+ This is the reference to the subtable, that is, it records the
+ fact that the identified table is inherited from some other
+ table.
+
+
+
+ |
+ inhparent
+ oid
+ pg_class.oid
+
+ This is the reference to the parent table, from which the table
+ referenced by inhrelid inherited
+ from.
+
+
+
+ |
+ inhseqno
+ int4
+
+
+ If there is more than one subtable/parent pair (multiple
+ inheritance), this number tells the order in which the
+ inherited columns are to be arranged. The count starts at 1.
+
+
+
+
+
+
+
+
+
+
+
pg_language
+
+ pg_language registers call interfaces or
+ languages in which you can write functions or stored procedures.
+ See under CREATE LANGUAGE and in the
+ Programmer's Guide for more information
+ about language handlers.
+
+
+
+
pg_language Columns
+
+
+
+ |
+ Name
+ Type
+ References
+ Description
+
+
+
+
+ |
+ lanname
+ name
+
+ Name of the language (to be specified when creating a function)
+
+
+ |
+ lanispl
+ bool
+
+
+ This is false for internal languages (such as SQL) and true for
+ dynamically loaded language handler modules. It essentially
+ means that, if it is true, the language may be dropped.
+
+
+
+ |
+ lanpltrusted
+ bool
+
+
+ This is a trusted language. See under CREATE
+ LANGUAGE what this means. If this is an internal
+ language (lanispl is false) then
+ this field is meaningless.
+
+
+
+ |
+ lanplcallfoid
+ oid
+ pg_proc.oid
+
+ For non-internal languages this references the language
+ handler, which is a special function that is responsible for
+ executing all functions that are written in the particular
+ language.
+
+
+
+ |
+ lancompiler
+ text
+
+ not useful
+
+
+
+
+
+
+
+
+
+
pg_operator
+
+ See CREATE OPERATOR and the
+ Programmer's Guide for details on these
+ operator parameters.
+
+
+
+
pg_operator Columns
+
+
+
+ |
+ Name
+ Type
+ References
+ Description
+
+
+
+
+ |
+ oprname
+ name
+
+ Name of the operator
+
+
+ |
+ oprowner
+ int4
+ pg_shadow.usesysid
+ Owner (creator) of the operator
+
+
+ |
+ oprprec
+ int2
+
+ unused
+
+
+ |
+ oprkind
+ char
+
+
+ 'b' = infix (both
), 'l' = prefix
+ (left
), 'r' = postfix (right
)
+
+
+
+ |
+ oprisleft
+ bool
+
+ unused
+
+
+ |
+ oprcanhash
+ bool
+
+ This operator supports hash joins.
+
+
+ |
+ oprleft
+ oid
+ pg_type.oid
+ Type of the left operand
+
+
+ |
+ oprright
+ oid
+ pg_type.oid
+ Type of the right operand
+
+
+ |
+ oprresult
+ oid
+ pg_type.oid
+ Type of the result
+
+
+ |
+ oprcom
+ oid
+ pg_operator.oid
+ Commutator of this operator, if any
+
+
+ |
+ oprnegate
+ oid
+ pg_operator.oid
+ Inverse of this operator, if any
+
+
+ |
+ oprlsortop
+ oid
+ pg_operator.oid
+
+ If this operator supports merge joins, the operator that sorts
+ the type of the left-hand operand
+
+
+
+ |
+ oprrsortop
+ oid
+ pg_operator.oid
+
+ If this operator supports merge joins, the operator that sorts
+ the type of the left-hand operand
+
+
+
+ |
+ oprcode
+ regproc
+
+ Function that implements this operator
+
+
+ |
+ oprrest
+ regproc
+
+ Restriction selectivity estimation function for this operator
+
+
+ |
+ oprjoin
+ regproc
+
+ Join selectivity estimation function for this operator
+
+
+
+
+
+
+
+
+
+
pg_proc
+
+ This catalog stores information about functions (or procedures).
+ The description of CREATE FUNCTION and the
+ Programmer's Guide contain more information
+ about the meaning of some fields.
+
+
+
+
pg_proc Columns
+
+
+
+ |
+ Name
+ Type
+ References
+ Description
+
+
+
+
+ |
+ proname
+ name
+
+ Name of the function
+
+
+ |
+ proowner
+ int4
+ pg_shadow.usesysid
+ Owner (creator) of the function
+
+
+ |
+ prolang
+ oid
+ pg_language.oid
+ Implementation language or call interface of this function
+
+
+ |
+ proisinh
+ bool
+
+ unused
+
+
+ |
+ proistrusted
+ bool
+
+ not functional
+
+
+ |
+ proiscachable
+ bool
+
+ Function returns same result for same input values
+
+
+ |
+ proisstrict
+ bool
+
+
+ Function returns null if any call argument is null. In that
+ case the function won't actually be called at all. Functions
+ that are not strict
must be prepared to handle
+ null inputs.
+
+
+
+ |
+ pronargs
+ int2
+
+ Number of arguments
+
+
+ |
+ proretset
+ bool
+
+ Function returns a set (probably not functional)
+
+
+ |
+ prorettype
+ oid
+ pg_type.oid
+ Data type of the return value (0 if the function does not return a value)
+
+
+ |
+ proargtypes
+ oidvector
+ pg_type.oid
+ A vector with the data types of the function arguments
+
+
+ |
+ probyte_pct
+ int4
+
+ dead code
+
+
+ |
+ properbyte_pct
+ int4
+
+ dead code
+
+
+ |
+ propercall_pct
+ int4
+
+ dead code
+
+
+ |
+ prooutin_ratio
+ int4
+
+ dead code
+
+
+ |
+ prosrc
+ text
+
+
+ This tells the function handler how to invoke the function. It
+ might be the actual source code of the function for interpreted
+ languages, a link symbol, a file name, or just about anything
+ else, depending the implementation language/call convention.
+
+
+
+ |
+ probin
+ bytea
+
+ ?
+
+
+
+
+
+
+
+
+
+
pg_relcheck
+
+ This system catalog stores CHECK constraints on tables. (Column
+ constraints are not treated specially. Every column constraint is
+ equivalent to some table constraint.) See under CREATE
+ TABLE for more information.
+
+
+
+
pg_relcheck Columns
+
+
+
+ |
+ Name
+ Type
+ References
+ Description
+
+
+
+
+ |
+ rcrelid
+ oid
+ pg_class.oid
+ The table this check constraint is on
+
+
+ |
+ rcname
+ name
+
+ Constraint name
+
+
+ |
+ rcbin
+ text
+
+ An internal representation of the constraint expression
+
+
+ |
+ rcsrc
+ text
+
+ A human-readable representation of the consraint expression
+
+
+
+
+
+
+ pg_class.relchecks
+ needs to match up with the entries in this table.
+
+
+
+
+
+
+
+
pg_shadow
+
+ pg_shadow contains information about
+ database users. The name stems from the fact that this table
+ should not be readable by the public since it contains passwords.
+ pg_user is a view on
+ pg_shadow that blanks out the password field.
+
+
+ The Administrator's Guide contains detailed
+ information about user and permission management.
+
+
+
+
pg_shadow Columns
+
+
+
+ |
+ Name
+ Type
+ References
+ Description
+
+
+
+
+ |
+ usename
+ name
+
+ User name
+
+
+ |
+ usesysid
+ int4
+
+ User id (arbitrary number used to reference this user)
+
+
+ |
+ usecreatedb
+ bool
+
+ User may create databases
+
+
+ |
+ usetrace
+ bool
+
+ not used
+
+
+ |
+ usesuper
+ bool
+
+ User is a superuser
+
+
+ |
+ usecatupd
+ bool
+
+
+ User may update system catalogs. (Even a superuser may not do
+ this unless this attribute is true.)
+
+
+
+ |
+ passwd
+ text
+
+ Password
+
+
+ |
+ valuntil
+ abstime
+
+ Account expiry time (only used for password authentication)
+
+
+
+
+
+
+
+
+
+
pg_type
+
+
+
pg_type Columns
+
+
+
+ |
+ Name
+ Type
+ References
+ Description
+
+
+
+
+ |
+ typname
+ name
+
+ Data type name
+
+
+ |
+ typowner
+ int4
+ pg_shadow.usesysid
+ Owner (creator) of the type
+
+
+ |
+ typlen
+ int2
+
+ Length of the storage representation of the type, -1 if variable length
+
+
+ |
+ typprtlen
+ int2
+
+ unused
+
+
+ |
+ typbyval
+ bool
+
+
+ typbyval determines whether internal
+ routines pass a value of this type by value or by reference.
+ Only char, short, and
+ int equivalent items can be passed by value, so if
+ the type is not 1, 2, or 4 bytes long, Postgres does not have
+ the option of passing by value and so
+ typbyval had better be false.
+ Variable-length types are always passed by reference. Note that
+ typbyval can be false even if the
+ length would allow pass-by-value; this is currently true for
+ type float4, for example.
+
+
+
+ |
+ typtype
+ char
+
+
+ typtype is b for
+ a basic type and c for a catalog type (i.e.,
+ a table). If typtype is
+ c, typrelid is
+ the OID of the type's entry in
+ pg_class.
+
+
+
+ |
+ typisdefined
+ bool
+
+ ???
+
+
+ |
+ typdelim
+ char
+
+ Character that separates two values of this type when parsing array input
+
+
+ |
+ typrelid
+ oid
+ pg_class.oid
+
+ If this is a catalog type (see
+ typtype), then this field points to
+ the pg_class entry that defines the
+ corresponding table. A table could theoretically be used as a
+ composite data type, but this is not fully functional.
+
+
+
+ |
+ typelem
+ oid
+ pg_type.oid
+
+ If typelem is not 0 then it
+ identifies another row in pg_type.
+ The current type can then be subscripted like an array yielding
+ values of type typelem. A non-zero
+ typelem does not guarantee this type
+ to be a real
array type; some ordinary
+ fixed-length types can also be subscripted (e.g.,
+ oidvector). Variable-length types can
+ not be turned into pseudo-arrays like
+ that. Hence, the way to determine whether a type is a
+ true
array type is typelem != 0 and typlen < 0.
+
+
+
+ |
+ typinput
+ regproc
+
+ Input function
+
+
+ |
+ typoutput
+ regproc
+
+ Output function
+
+
+ |
+ typreceive
+ regproc
+
+ unused
+
+
+ |
+ typsend
+ regproc
+
+ unused
+
+
+ |
+ typalign
+ char
+
+
+ typalign is the alignment required
+ when storing a value of this type. It applies to storage on
+ disk as well as most representations of the value inside
+ Postgres. When multiple values are stored consecutively, such
+ as in the representation of a complete row on disk, padding is
+ inserted before a datum of this type so that it begins on the
+ specified boundary. The alignment reference is the beginning
+ of the first datum in the sequence.
+ Possible values are:
+
+
+
'c' = CHAR alignment, ie no alignment needed.+
+
+
's' = SHORT alignment (2 bytes on most machines).+
+
+
'i' = INT alignment (4 bytes on most machines).+
+
+
'd' = DOUBLE alignment (8 bytes on many machines, but by no means all).+
+
+
+ For types used in system tables, it is critical that the size
+ and alignment defined in pg_type
+ agree with the way that the compiler will lay out the field in
+ a struct representing a table row.
+
+
+
+
+ |
+ typstorage
+ char
+
+ typstorage tells for variable-length
+ types (those with typlen = -1) if
+ the type is prepared for toasting and what the default strategy
+ for attributes of this type should be.
+ Possible values are
+
+
+
'p': Value must always be stored plain.+
+
+ 'e': Value can be stored in a secondary
+ relation (if relation has one, see
+ pg_class.reltoastrelid).
+
+
+
+
'm': Value can be stored compressed inline.+
+
+
'x': Value can be stored compressed inline or in secondary
.+
+
+ Note that 'm' fields can also be moved out to secondary
+ storage, but only as a last resort ('e' and 'x' fields are
+ moved first).
+
+
+
+ |
+ typdefault
+ text
+
+ ???
+
+
+
+
+
+
+
+
projects / postgresql.git / commitdiff