doc: Document more that relations share a namespace
This was already documented in the CREATE INDEX reference, but not in the introductory "Data Definition" chapter. Also, document that the index that implements a constraint has the same name as the constraint. Author: Laurenz Albe <laurenz.albe@cybertec.at> Reviewed-by: jian he <jian.universality@gmail.com> Reviewed-by: David G. Johnston <david.g.johnston@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CACJufxFG682tYcP9aH_F-jrqq5End8MHZR77zcp1%3DDUrEsSu1Q%40mail.gmail.com
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@ -3003,7 +3003,11 @@ SELECT * FROM information WHERE group_id = 2 FOR UPDATE;
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<para>
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<para>
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A database contains one or more named <firstterm>schemas</firstterm>, which
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A database contains one or more named <firstterm>schemas</firstterm>, which
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in turn contain tables. Schemas also contain other kinds of named
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in turn contain tables. Schemas also contain other kinds of named
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objects, including data types, functions, and operators. The same
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objects, including data types, functions, and operators. Within one
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schema, two objects of the same type cannot have the same name.
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Furthermore, tables, sequences, indexes, views, materialized views, and
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foreign tables share the same namespace, so that, for example, an index and
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a table must have different names if they are in the same schema. The same
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object name can be used in different schemas without conflict; for
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object name can be used in different schemas without conflict; for
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example, both <literal>schema1</literal> and <literal>myschema</literal> can
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example, both <literal>schema1</literal> and <literal>myschema</literal> can
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contain tables named <literal>mytable</literal>. Unlike databases,
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contain tables named <literal>mytable</literal>. Unlike databases,
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@ -1027,7 +1027,8 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
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Adding a unique constraint will automatically create a unique B-tree
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Adding a unique constraint will automatically create a unique B-tree
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index on the column or group of columns used in the constraint. But if
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index on the column or group of columns used in the constraint. But if
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the constraint includes a <literal>WITHOUT OVERLAPS</literal> clause, it
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the constraint includes a <literal>WITHOUT OVERLAPS</literal> clause, it
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will use a GiST index.
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will use a GiST index. The created index has the same name as the unique
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constraint.
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</para>
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</para>
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<para>
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<para>
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@ -1082,6 +1083,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
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<literal>PRIMARY KEY</literal> constraint will automatically create a
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<literal>PRIMARY KEY</literal> constraint will automatically create a
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unique B-tree index, or GiST if <literal>WITHOUT OVERLAPS</literal> was
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unique B-tree index, or GiST if <literal>WITHOUT OVERLAPS</literal> was
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specified, on the column or group of columns used in the constraint.
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specified, on the column or group of columns used in the constraint.
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That index has the same name as the primary key constraint.
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</para>
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</para>
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<para>
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<para>
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@ -1118,8 +1120,8 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
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<para>
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<para>
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Exclusion constraints are implemented using
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Exclusion constraints are implemented using
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an index, so each specified operator must be associated with an
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an index that has the same name as the constraint, so each specified
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appropriate operator class
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operator must be associated with an appropriate operator class
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(see <xref linkend="indexes-opclass"/>) for the index access
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(see <xref linkend="indexes-opclass"/>) for the index access
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method <replaceable>index_method</replaceable>.
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method <replaceable>index_method</replaceable>.
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The operators are required to be commutative.
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The operators are required to be commutative.
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