- linkend="functions-string-sql"/>. For other cases, insert an explicit
- coercion to text if you need to duplicate the previous behavior.
+ The string concatenation operator (||) will accept
+ non-string input, so long as at least one input is of string type, as shown
+ in . For other cases, inserting an
+ explicit coercion to text can be used to have non-string input
+ accepted.
(last subscript varies most rapidly).
If the contents of two arrays are equal but the dimensionality is
different, the first difference in the dimensionality information
- determines the sort order. (This is a change from versions of
-
PostgreSQL prior to 8.2: older versions would claim
- that two arrays with the same contents were equal, even if the
- number of dimensions or subscript ranges were different.)
+ determines the sort order.
Updating a
GIN index tends to be slow because of the
intrinsic nature of inverted indexes: inserting or updating one heap row
can cause many inserts into the index (one for each key extracted
- from the indexed item).
As of PostgreSQL 8.4,
+ from the indexed item).
GIN is capable of postponing much of this work by inserting
new tuples into a temporary, unsorted list of pending entries.
When the table is vacuumed or autoanalyzed, or when
- As of
PostgreSQL 8.4, this advice is less
- necessary since delayed indexing is used (see
- linkend="gin-fast-update"/> for details). But for very large updates
- it may still be best to drop and recreate the index.
+ When
fastupdate is enabled for
GIN
+ (see for details), the penalty is
+ less than when it is not. But for very large updates it may still be
+ best to drop and recreate the index.
by introducing a dummy one-row table from which to do the
SELECT.
-
- Note that if a FROM clause is not specified,
- the query cannot reference any database tables. For example, the
- following query is invalid:
-SELECT distributors.* WHERE distributors.name = 'Westward';
-
PostgreSQL releases prior to
- 8.1 would accept queries of this form, and add an implicit entry
- to the query's FROM clause for each table
- referenced by the query. This is no longer allowed.
-