Doc: consistently identify OID catalog columns that can be zero.

Not all OID-reference columns that can contain zeroes (indicating
"no reference") were explicitly marked in catalogs.sgml.  Fix that,
and try to make the style a little more consistent while at it ---
for example, consistently write "zero" not "0" for these cases.

Joel Jacobson and Tom Lane

Discussion: https://postgr.es/m/4ed9a372-7bf9-479a-926c-ae8e774717a8@www.fastmail.com

diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 865e826fb0b3463ef14cf0a960405fdc5bd4e973..ea222c04640b123c2cf54f36f60be987bfb354a6 100644 (file)
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -1150,7 +1150,7 @@
        (references pg_type.oid)
       
       
-       The data type of this column
+       The data type of this column (zero for a dropped column)
       
      
 
@@ -1351,7 +1351,7 @@
       
       
        The defined collation of the column, or zero if the column is
-       not of a collatable data type.
+       not of a collatable data type
       
      
 
@@ -1899,8 +1899,8 @@ SCRAM-SHA-256$<iteration count>:&l
       
       
        The OID of the data type that corresponds to this table's row type,
-       if any (zero for indexes, sequences, and toast tables, which have
-       no pg_type entry)
+       if any; zero for indexes, sequences, and toast tables, which have
+       no pg_type entry
       
      
 
@@ -1910,7 +1910,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_type.oid)
       
       
-       For typed tables, the OID of the underlying composite type,
+       For typed tables, the OID of the underlying composite type;
        zero for all other relations
       
      
@@ -1932,7 +1932,8 @@ SCRAM-SHA-256$<iteration count>:&l
       
       
        If this is a table or an index, the access method used (heap,
-       B-tree, hash, etc.)
+       B-tree, hash, etc.); otherwise zero (zero occurs for sequences,
+       as well as relations without storage, such as views)
       
      
 
@@ -2007,7 +2008,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_class.oid)
       
       
-       OID of the TOAST table associated with this table, 0 if none.  The
+       OID of the TOAST table associated with this table, zero if none.  The
        TOAST table stores large attributes out of line in a
        secondary table.
       
@@ -2174,8 +2175,8 @@ SCRAM-SHA-256$<iteration count>:&l
       
        For new relations being written during a DDL operation that requires a
        table rewrite, this contains the OID of the original relation;
-       otherwise 0.  That state is only visible internally; this field should
-       never contain anything other than 0 for a user-visible relation.
+       otherwise zero.  That state is only visible internally; this field should
+       never contain anything other than zero for a user-visible relation.
       
      
 
@@ -2507,7 +2508,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_class.oid)
       
       
-       The table this constraint is on; 0 if not a table constraint
+       The table this constraint is on; zero if not a table constraint
       
      
 
@@ -2517,7 +2518,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_type.oid)
       
       
-       The domain this constraint is on; 0 if not a domain constraint
+       The domain this constraint is on; zero if not a domain constraint
       
      
 
@@ -2528,7 +2529,7 @@ SCRAM-SHA-256$<iteration count>:&l
       
       
        The index supporting this constraint, if it's a unique, primary
-       key, foreign key, or exclusion constraint; else 0
+       key, foreign key, or exclusion constraint; else zero
       
      
 
@@ -2538,8 +2539,8 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_constraint.oid)
       
       
-       The corresponding constraint in the parent partitioned table,
-       if this is a constraint in a partition; else 0
+       The corresponding constraint of the parent partitioned table,
+       if this is a constraint on a partition; else zero
       
      
 
@@ -2549,7 +2550,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_class.oid)
       
       
-       If a foreign key, the referenced table; else 0
+       If a foreign key, the referenced table; else zero
       
      
 
@@ -3142,7 +3143,7 @@ SCRAM-SHA-256$<iteration count>:&l
       
       
        The OID of the namespace associated with this entry,
-       or 0 if none
+       or zero if none
       
      
 
@@ -3176,7 +3177,7 @@ SCRAM-SHA-256$<iteration count>:&l
    A pg_default_acl entry shows the initial privileges to
    be assigned to an object belonging to the indicated user.  There are
    currently two types of entry: global entries with
-   defaclnamespace = 0, and per-schema entries
+   defaclnamespace = zero, and per-schema entries
    that reference a particular schema.  If a global entry is present then
    it overrides the normal hard-wired default privileges
    for the object type.  A per-schema entry, if present, represents privileges
@@ -3236,7 +3237,8 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_class.oid)
       
       
-       The OID of the system catalog the dependent object is in
+       The OID of the system catalog the dependent object is in,
+       or zero for a DEPENDENCY_PIN entry
       
      
 
@@ -3246,7 +3248,8 @@ SCRAM-SHA-256$<iteration count>:&l
        (references any OID column)
       
       
-       The OID of the specific dependent object
+       The OID of the specific dependent object,
+       or zero for a DEPENDENCY_PIN entry
       
      
 
@@ -4687,7 +4690,7 @@ SCRAM-SHA-256$<iteration count>:&l
        For noninternal 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
+       language. Zero for internal languages.
       
      
 
@@ -5189,7 +5192,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_type.oid)
       
       
-       Type of the left operand (0 if none)
+       Type of the left operand (zero for a prefix operator)
       
      
 
@@ -5210,6 +5213,7 @@ SCRAM-SHA-256$<iteration count>:&l
       
       
        Type of the result
+       (zero for a not-yet-defined shell operator)
       
      
 
@@ -5219,7 +5223,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_operator.oid)
       
       
-       Commutator of this operator, if any
+       Commutator of this operator (zero if none)
       
      
 
@@ -5229,7 +5233,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_operator.oid)
       
       
-       Negator of this operator, if any
+       Negator of this operator (zero if none)
       
      
 
@@ -5240,6 +5244,7 @@ SCRAM-SHA-256$<iteration count>:&l
       
       
        Function that implements this operator
+       (zero for a not-yet-defined shell operator)
       
      
 
@@ -5250,6 +5255,7 @@ SCRAM-SHA-256$<iteration count>:&l
       
       
        Restriction selectivity estimation function for this operator
+       (zero if none)
       
      
 
@@ -5260,17 +5266,13 @@ SCRAM-SHA-256$<iteration count>:&l
       
       
        Join selectivity estimation function for this operator
+       (zero if none)
       
      
     
    
   
 
-  
-   Unused columns contain zeroes. For example, oprleft
-   is zero for a prefix operator.
-  
-
  
 
 
@@ -5426,7 +5428,7 @@ SCRAM-SHA-256$<iteration count>:&l
        partnatts int2
       
       
-       The number of columns in partition key
+       The number of columns in the partition key
       
      
 
@@ -5438,7 +5440,7 @@ SCRAM-SHA-256$<iteration count>:&l
       
        The OID of the pg_class entry for the default partition
        of this partitioned table, or zero if this partitioned table does not
-       have a default partition.
+       have a default partition
       
      
 
@@ -5588,7 +5590,9 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_authid.oid)
       
       
-       The roles to which the policy is applied
+       The roles to which the policy is applied;
+       zero means PUBLIC
+       (and normally appears alone in the array)
       
      
 
@@ -5744,8 +5748,8 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_proc.oid)
       
       
-       Optional planner support function for this function
-       (see )
+       Planner support function for this function
+       (see ), or zero if none
       
      
 
@@ -6256,7 +6260,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_collation.oid)
       
       
-       OID of the collation used for range comparisons, or 0 if none
+       OID of the collation used for range comparisons, or zero if none
       
      
 
@@ -6277,7 +6281,7 @@ SCRAM-SHA-256$<iteration count>:&l
       
       
        OID of the function to convert a range value into canonical form,
-       or 0 if none
+       or zero if none
       
      
 
@@ -6288,7 +6292,7 @@ SCRAM-SHA-256$<iteration count>:&l
       
       
        OID of the function to return the difference between two element
-       values as double precision, or 0 if none
+       values as double precision, or zero if none
       
      
     
@@ -6733,6 +6737,7 @@ SCRAM-SHA-256$<iteration count>:&l
       
        The OID of the database the dependent object is in,
        or zero for a shared object
+       or a SHARED_DEPENDENCY_PIN entry
       
      
 
@@ -6742,7 +6747,8 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_class.oid)
       
       
-       The OID of the system catalog the dependent object is in
+       The OID of the system catalog the dependent object is in,
+       or zero for a SHARED_DEPENDENCY_PIN entry
       
      
 
@@ -6752,7 +6758,8 @@ SCRAM-SHA-256$<iteration count>:&l
        (references any OID column)
       
       
-       The OID of the specific dependent object
+       The OID of the specific dependent object,
+       or zero for a SHARED_DEPENDENCY_PIN entry
       
      
 
@@ -7192,6 +7199,7 @@ SCRAM-SHA-256$<iteration count>:&l
        Nth slot.  For example, a
        histogram slot would show the < operator
        that defines the sort order of the data.
+       Zero if the statistics kind does not require an operator.
       
      
 
@@ -7836,7 +7844,7 @@ SCRAM-SHA-256$<iteration count>:&l
       
        The OID of the function to use when converting the data type for input
        to the procedural language (e.g., function parameters).  Zero is stored
-       if this operation is not supported.
+       if the default behavior should be used.
       
      
 
@@ -7848,7 +7856,7 @@ SCRAM-SHA-256$<iteration count>:&l
       
        The OID of the function to use when converting output from the
        procedural language (e.g., return values) to the data type.  Zero is
-       stored if this operation is not supported.
+       stored if the default behavior should be used.
       
      
     
@@ -7911,9 +7919,9 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_trigger.oid)
       
       
-       Parent trigger that this trigger is cloned from, zero if not a clone;
-       this happens when partitions are created or attached to a partitioned
-       table.
+       Parent trigger that this trigger is cloned from (this happens when
+       partitions are created or attached to a partitioned table);
+       zero if not a clone
       
      
 
@@ -7976,6 +7984,7 @@ SCRAM-SHA-256$<iteration count>:&l
       
       
        The table referenced by a referential integrity constraint
+       (zero if trigger is not for a referential integrity constraint)
       
      
 
@@ -7987,6 +7996,7 @@ SCRAM-SHA-256$<iteration count>:&l
       
        The index supporting a unique, primary key, referential integrity,
        or exclusion constraint
+       (zero if trigger is not for one of these types of constraint)
       
      
 
@@ -7996,7 +8006,8 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_constraint.oid)
       
       
-       The pg_constraint entry associated with the trigger, if any
+       The pg_constraint entry associated with the trigger
+       (zero if trigger is not for a constraint)
       
      
 
@@ -8478,7 +8489,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_proc.oid)
       
       
-       OID of the parser's headline function
+       OID of the parser's headline function (zero if none)
       
      
 
@@ -8566,7 +8577,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_proc.oid)
       
       
-       OID of the template's initialization function
+       OID of the template's initialization function (zero if none)
       
      
 
@@ -8786,11 +8797,11 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_type.oid)
       
       
-       If typelem is not 0 then it
+       If typelem is not zero then it
        identifies another row in pg_type,
-       defining the type yielded by subscripting.  This should be 0
-       if typsubscript is 0.  However, it can
-       be 0 when typsubscript isn't 0, if the
+       defining the type yielded by subscripting.  This should be zero
+       if typsubscript is zero.  However, it can
+       be zero when typsubscript isn't zero, if the
        handler doesn't need typelem to
        determine the subscripting result type.
        Note that a typelem dependency is
@@ -8806,7 +8817,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_type.oid)
       
       
-       If typarray is not 0 then it
+       If typarray is not zero then it
        identifies another row in pg_type, which
        is the true array type having this type as element
       
@@ -8838,7 +8849,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_proc.oid)
       
       
-       Input conversion function (binary format), or 0 if none
+       Input conversion function (binary format), or zero if none
       
      
 
@@ -8848,7 +8859,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_proc.oid)
       
       
-       Output conversion function (binary format), or 0 if none
+       Output conversion function (binary format), or zero if none
       
      
 
@@ -8858,7 +8869,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_proc.oid)
       
       
-       Type modifier input function, or 0 if type does not support modifiers
+       Type modifier input function, or zero if type does not support modifiers
       
      
 
@@ -8868,7 +8879,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_proc.oid)
       
       
-       Type modifier output function, or 0 to use the standard format
+       Type modifier output function, or zero to use the standard format
       
      
 
@@ -8878,7 +8889,8 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_proc.oid)
       
       
-       Custom  function, or 0 to use the standard function
+       Custom  function,
+       or zero to use the standard function
       
      
 
@@ -9198,7 +9210,7 @@ SCRAM-SHA-256$<iteration count>:&l
        (references pg_authid.oid)
       
       
-       OID of the local role being mapped, 0 if the user mapping is public
+       OID of the local role being mapped, or zero if the user mapping is public
       
      
 
@@ -13403,7 +13415,7 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx
        (references pg_authid.oid)
       
       
-       OID of the local role being mapped, 0 if the user mapping is public
+       OID of the local role being mapped, or zero if the user mapping is public