handle multiple 'formats' for data I/O. Restructure CommandDest and
DestReceiver stuff one more time (it's finally starting to look a bit
clean though). Code now matches latest 3.0 protocol document as far
as message formats go --- but there is no support for binary I/O yet.
DestReceiver pointers instead of just CommandDest values. The DestReceiver
is made at the point where the destination is selected, rather than
deep inside the executor. This cleans up the original kluge implementation
of tstoreReceiver.c, and makes it easy to support retrieving results
from utility statements inside portals. Thus, you can now do fun things
like Bind and Execute a FETCH or EXPLAIN command, and it'll all work
as expected (e.g., you can Describe the portal, or use Execute's count
parameter to suspend the output partway through). Implementation involves
stuffing the utility command's output into a Tuplestore, which would be
kind of annoying for huge output sets, but should be quite acceptable
for typical uses of utility commands.
the column by table OID and column number, if it's a simple column
reference. Along the way, get rid of reskey/reskeyop fields in Resdoms.
Turns out that representation was not convenient for either the planner
or the executor; we can make the planner deliver exactly what the
executor wants with no more effort.
initdb forced due to change in stored rule representation.
a per-query memory context created by CreateExecutorState --- and destroyed
by FreeExecutorState. This provides a final solution to the longstanding
problem of memory leaked by various ExecEndNode calls.
to plan nodes, not vice-versa. All executor state nodes now inherit from
struct PlanState. Copying of plan trees has been simplified by not
storing a list of SubPlans in Plan nodes (eliminating duplicate links).
The executor still needs such a list, but it can build it during
ExecutorStart since it has to scan the plan tree anyway.
No initdb forced since no stored-on-disk structures changed, but you
will need a full recompile because of node-numbering changes.
of functions returning domain types, update documentation for typtype,
move get_typtype to lsyscache.c (actually, resurrect the old version),
add defense against creating pseudo-typed table columns, fix some
bogus list-parsing in grammar. Issues remain with respect to alias
handling and type checking; Joe is on those.
types for Table Functions, as previously proposed on HACKERS. Here is a
brief explanation:
1. Creates a new pg_type typtype: 'p' for pseudo type (currently either
'b' for base or 'c' for catalog, i.e. a class).
2. Creates new builtin type of typtype='p' named RECORD. This is the
first of potentially several pseudo types.
3. Modify FROM clause grammer to accept:
SELECT * FROM my_func() AS m(colname1 type1, colname2 type1, ...)
where m is the table alias, colname1, etc are the column names, and
type1, etc are the column types.
4. When typtype == 'p' and the function return type is RECORD, a list
of column defs is required, and when typtype != 'p', it is
disallowed.
5. A check was added to ensure that the tupdesc provide via the parser
and the actual return tupdesc match in number and type of
attributes.
When creating a function you can do:
CREATE FUNCTION foo(text) RETURNS setof RECORD ...
When using it you can do:
SELECT * from foo(sqlstmt) AS (f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) AS f(f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) f(f1 int, f2 text, f3 timestamp)
Included in the patches are adjustments to the regression test sql and
expected files, and documentation.
p.s.
This potentially solves (or at least improves) the issue of builtin
Table Functions. They can be bootstrapped as returning RECORD, and
we can wrap system views around them with properly specified column
defs. For example:
CREATE VIEW pg_settings AS
SELECT s.name, s.setting
FROM show_all_settings()AS s(name text, setting text);
Then we can also add the UPDATE RULE that I previously posted to
pg_settings, and have pg_settings act like a virtual table, allowing
settings to be queried and set.
Joe Conway
in snapshots, per my proposal of a few days ago. Also, tweak heapam.c
routines (heap_insert, heap_update, heap_delete, heap_mark4update) to
be passed the command ID to use, instead of doing GetCurrentCommandID.
For catalog updates they'll still get passed current command ID, but
for updates generated from the main executor they'll get passed the
command ID saved in the snapshot the query is using. This should fix
some corner cases associated with functions and triggers that advance
current command ID while an outer query is still in progress.
some kibitzing from Tom Lane. Not everything works yet, and there's
no documentation or regression test, but let's commit this so Joe
doesn't need to cope with tracking changes in so many files ...
are now both invoked once per received SQL command (raw parsetree) from
pg_exec_query_string. BeginCommand is actually just an empty routine
at the moment --- all its former operations have been pushed into tuple
receiver setup routines in printtup.c. This makes for a clean distinction
between BeginCommand/EndCommand (once per command) and the tuple receiver
setup/teardown routines (once per ExecutorRun call), whereas the old code
was quite ad hoc. Along the way, clean up the calling conventions for
ExecutorRun a little bit.
report for each received SQL command, regardless of rewriting activity.
Also ensure that this report comes from the 'original' command, not the
last command generated by rewrite; this fixes 7.2 breakage for INSERT
commands that have actions added by rules. Fernando Nasser and Tom Lane.
allocated by plan nodes are not leaked at end of query. This doesn't
really matter for normal queries, but it sure does for queries invoked
repetitively inside SQL functions. Clean up some other grotty code
associated with tupdescs, and fix a few other memory leaks exposed by
tests with simple SQL functions.
maintained for each cache entry. A cache entry will not be freed until
the matching ReleaseSysCache call has been executed. This eliminates
worries about cache entries getting dropped while still in use. See
my posting to pg-hackers of even date for more info.
joins, and clean things up a good deal at the same time. Append plan node
no longer hacks on rangetable at runtime --- instead, all child tables are
given their own RT entries during planning. Concept of multiple target
tables pushed up into execMain, replacing bug-prone implementation within
nodeAppend. Planner now supports generating Append plans for inheritance
sets either at the top of the plan (the old way) or at the bottom. Expanding
at the bottom is appropriate for tables used as sources, since they may
appear inside an outer join; but we must still expand at the top when the
target of an UPDATE or DELETE is an inheritance set, because we actually need
a different targetlist and junkfilter for each target table in that case.
Fortunately a target table can't be inside an outer join... Bizarre mutual
recursion between union_planner and prepunion.c is gone --- in fact,
union_planner doesn't really have much to do with union queries anymore,
so I renamed it grouping_planner.
ExecutorRun. This allows LIMIT to work in a view. Also, LIMIT in a
cursor declaration will behave in a reasonable fashion, whereas before
it was overridden by the FETCH count.
for example, an SQL function can be used in a functional index. (I make
no promises about speed, but it'll work ;-).) Clean up and simplify
handling of functions returning sets.
from Param nodes, per discussion a few days ago on pghackers. Add new
expression node type FieldSelect that implements the functionality where
it's actually needed. Clean up some other unused fields in Func nodes
as well.
NOTE: initdb forced due to change in stored expression trees for rules.
memory contexts. Currently, only leaks in expressions executed as
quals or projections are handled. Clean up some old dead cruft in
executor while at it --- unused fields in state nodes, that sort of thing.
for details). It doesn't really do that much yet, since there are no
short-term memory contexts in the executor, but the infrastructure is
in place and long-term contexts are handled reasonably. A few long-
standing bugs have been fixed, such as 'VACUUM; anything' in a single
query string crashing. Also, out-of-memory is now considered a
recoverable ERROR, not FATAL.
Eliminate a large amount of crufty, now-dead code in and around
memory management.
Fix problem with holding off SIGTRAP, SIGSEGV, etc in postmaster and
backend startup.
key call sites are changed, but most called functions are still oldstyle.
An exception is that the PL managers are updated (so, for example, NULL
handling now behaves as expected in plperl and plpgsql functions).
NOTE initdb is forced due to added column in pg_proc.
would crash, due to premature invocation of SetQuerySnapshot(). Clean
up problems with handling of multiple queries by splitting
pg_parse_and_plan into two routines. The old code would not, for
example, do the right thing with END; SELECT... submitted in one query
string when it had been in transaction abort state, because it'd decide
to skip planning the SELECT before it had executed the END. New
arrangement is simpler and doesn't force caller to plan if only
parse+rewrite is needed.
lists are now plain old garden-variety Lists, allocated with palloc,
rather than specialized expansible-array data allocated with malloc.
This substantially simplifies their handling and eliminates several
sources of memory leakage.
Several basic types of erroneous queries (syntax error, attempt to
insert a duplicate key into a unique index) now demonstrably leak
zero bytes per query.
patch is applied:
Rewrite rules on relation level work fine now.
Event qualifications on insert/update/delete rules work
fine now.
I added the new keyword OLD to reference the CURRENT
tuple. CURRENT will be removed in 6.5.
Update rules can reference NEW and OLD in the rule
qualification and the actions.
Insert/update/delete rules on views can be established to
let them behave like real tables.
For insert/update/delete rules multiple actions are
supported now. The actions can also be surrounded by
parantheses to make psql happy. Multiple actions are
required if update to a view requires updates to multiple
tables.
Regular users are permitted to create/drop rules on
tables they have RULE permissions for
(DefineQueryRewrite() is now able to get around the
access restrictions on pg_rewrite). This enables view
creation for regular users too. This required an extra
boolean parameter to pg_parse_and_plan() that tells to
set skipAcl on all rangetable entries of the resulting
queries. There is a new function
pg_exec_query_acl_override() that could be used by
backend utilities to use this facility.
All rule actions (not only views) inherit the permissions
of the event relations owner. Sample: User A creates
tables T1 and T2, creates rules that log
INSERT/UPDATE/DELETE on T1 in T2 (like in the regression
tests for rules I created) and grants ALL but RULE on T1
to user B. User B can now fully access T1 and the
logging happens in T2. But user B cannot access T2 at
all, only the rule actions can. And due to missing RULE
permissions on T1, user B cannot disable logging.
Rules on the attribute level are disabled (they don't
work properly and since regular users are now permitted
to create rules I decided to disable them).
Rules on select must have exactly one action that is a
select (so select rules must be a view definition).
UPDATE NEW/OLD rules are disabled (still broken, but
triggers can do it).
There are two new system views (pg_rule and pg_view) that
show the definition of the rules or views so the db admin
can see what the users do. They use two new functions
pg_get_ruledef() and pg_get_viewdef() that are builtins.
The functions pg_get_ruledef() and pg_get_viewdef() could
be used to implement rule and view support in pg_dump.
PostgreSQL is now the only database system I know, that
has rewrite rules on the query level. All others (where I
found a rule statement at all) use stored database
procedures or the like (triggers as we call them) for
active rules (as some call them).
Future of the rule system:
The now disabled parts of the rule system (attribute
level, multiple actions on select and update new stuff)
require a complete new rewrite handler from scratch. The
old one is too badly wired up.
After 6.4 I'll start to work on a new rewrite handler,
that fully supports the attribute level rules, multiple
actions on select and update new. This will be available
for 6.5 so we get full rewrite rule capabilities.
Jan
