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ALTER TABLE rewrite. New cool stuff:

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* ALTER ... ADD COLUMN with defaults and NOT NULL constraints works per SQL
spec.  A default is implemented by rewriting the table with the new value
stored in each row.

* ALTER COLUMN TYPE.  You can change a column's datatype to anything you
want, so long as you can specify how to convert the old value.  Rewrites
the table.  (Possible future improvement: optimize no-op conversions such
as varchar(N) to varchar(N+1).)

* Multiple ALTER actions in a single ALTER TABLE command.  You can perform
any number of column additions, type changes, and constraint additions with
only one pass over the table contents.

Basic documentation provided in ALTER TABLE ref page, but some more docs
work is needed.

Original patch from Rod Taylor, additional work from Tom Lane.
This commit is contained in:
Tom Lane
2004-05-05 04:48:48 +00:00
parent 3e3cb0a14a
commit 077db40fa1
30 changed files with 3302 additions and 1906 deletions
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27
src/backend/catalog/index.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/catalog/index.c,v 1.228 2004/02/15 21:01:39 tgl Exp $
* $PostgreSQL: pgsql/src/backend/catalog/index.c,v 1.229 2004/05/05 04:48:45 tgl Exp $
*
*
* INTERFACE ROUTINES
@@ -470,7 +470,8 @@ index_create(Oid heapRelationId,
Oid *classObjectId,
bool primary,
bool isconstraint,
bool allow_system_table_mods)
bool allow_system_table_mods,
bool skip_build)
{
Relation heapRelation;
Relation indexRelation;
@@ -721,21 +722,31 @@ index_create(Oid heapRelationId,
* If this is bootstrap (initdb) time, then we don't actually fill in
* the index yet. We'll be creating more indexes and classes later,
* so we delay filling them in until just before we're done with
* bootstrapping. Otherwise, we call the routine that constructs the
* index.
* bootstrapping. Similarly, if the caller specified skip_build then
* filling the index is delayed till later (ALTER TABLE can save work
* in some cases with this). Otherwise, we call the AM routine that
* constructs the index.
*
* In normal processing mode, the heap and index relations are closed by
* index_build() --- but we continue to hold the ShareLock on the heap
* and the exclusive lock on the index that we acquired above, until
* end of transaction.
* In normal processing mode, the heap and index relations are closed,
* but we continue to hold the ShareLock on the heap and the exclusive
* lock on the index that we acquired above, until end of transaction.
*/
if (IsBootstrapProcessingMode())
{
index_register(heapRelationId, indexoid, indexInfo);
/* XXX shouldn't we close the heap and index rels here? */
}
else if (skip_build)
{
/* caller is responsible for filling the index later on */
relation_close(indexRelation, NoLock);
heap_close(heapRelation, NoLock);
}
else
{
index_build(heapRelation, indexRelation, indexInfo);
/* index_build closes the passed rels */
}
return indexoid;
}