DROP DATABASE IF EXISTS variant

process of dropping roles by dropping objects owned by them and privileges
granted to them, or giving the owned objects to someone else, through the
use of the data stored in the new pg_shdepend catalog.

Some refactoring of the GRANT/REVOKE code was needed, as well as ALTER OWNER
code.  Further cleanup of code duplication in the GRANT code seems necessary.

Implemented by me after an idea from Tom Lane, who also provided various kind
of implementation advice.

Regression tests pass.  Some tests for the new functionality are also added,
as well as rudimentary documentation.

        - supports multibyte encodings
        - more strict rules for lexemes
        - flex isn't used
Add:
        - tsquery plainto_tsquery(text)
          Function makes tsquery from plain text.
        - &&, ||, !! operation for tsquery for combining
          tsquery from it's parts:  'foo & bar' || 'asd' => 'foo & bar | asd'

the convenience of tuptoaster.c and is no longer needed, so may as well
get rid of some small amount of overhead.

tuple in-place, but instead passes back an all-new tuple structure if
any changes are needed.  This is a much cleaner and more robust solution
for the bug discovered by Alexey Beschiokov; accordingly, revert the
quick hack I installed yesterday.
With this change, HeapTupleData.t_datamcxt is no longer needed; will
remove it in a separate commit in HEAD only.

doing heap_insert or heap_update, wipe out any extracted fields in
the TupleTableSlot containing the tuple, because they might not be valid
anymore if tuptoaster.c changed the tuple.  Safe because slot must be
in the materialized state, but mighty ugly --- find a better answer!

not only the array contents, before claiming two arrays are equal.
Per recent discussion.

DROP objecttype IF EXISTS for the following objects:
  table view index sequence schema type domain conversion

more tests than strictly necessary, but did not feel like tracing call
paths in detail ...

be useful to actually do something with nulls, rather than reject them,
but I'll just close the hole for now.

the array (for array_push) or higher-dimensional array (for array_cat)
rather than decrementing it as before.  This avoids generating lower
bounds other than one for any array operation within the SQL spec.  Per
recent discussion.
Interestingly, this seems to have been the original behavior, because
while updating the docs I noticed that a large fraction of relevant
examples were *wrong* for the old behavior and are now right.  Is it
worth correcting this in the back-branch docs?

recursed twice on its first argument, leading to exponential time spent
on a deep nest of COALESCEs ... such as a deeply nested FULL JOIN would
produce.  Per report from Matt Carter.

translate undef to NULL for result arrayref, now that we allow NULLs in arrays. Update plperl regression test accordingly.

contents directly.

J.Kuwamura

make psql honor explicit database parameter in -l mode, in case "postgres" database is missing - per complaint from Philip Yarra.

functionality, but I still need to make another pass looking at places
that incidentally use arrays (such as ACL manipulation) to make sure they
are null-safe.  Contrib needs work too.
I have not changed the behaviors that are still under discussion about
array comparison and what to do with lower bounds.

that was added to localbuf.c in 8.1; therefore, applying it to a temp table
left corrupt lookup state in memory.  The only case where this had a
significant chance of causing problems was an ON COMMIT DELETE ROWS temp
table; the other possible paths left bogus state that was unlikely to
be used again.  Per report from Csaba Nagy.

<   so duplicate checking can be easily performed.
>   so duplicate checking can be easily performed.  It is possible to
>   do it without a unique index if we require the user to LOCK the table
>   before the MERGE.

its result when the clause was an OR clause.  Brain fade exposed by
example from Sebastian BÎck.

< * Add a libpq function to support Parse/DescribeStatement capability
< * Add PQescapeIdentifier() to libpq
< * Prevent PQfnumber() from lowercasing unquoted the column name
<
<   PQfnumber() should never have been doing lowercasing, but historically
<   it has so we need a way to prevent it
<
648a642,661
>
>
> libpq
>
> 	o Add a function to support Parse/DescribeStatement capability
> 	o Add PQescapeIdentifier()
> 	o Prevent PQfnumber() from lowercasing unquoted the column name
>
> 	  PQfnumber() should never have been doing lowercasing, but
> 	  historically it has so we need a way to prevent it
>
> 	o Allow query results to be automatically batched to the client
>
> 	  Currently, all query results are transfered to the libpq
> 	  client before libpq makes the results available to the
> 	  application.  This feature would allow the application to make
> 	  use of the first result rows while the rest are transfered, or
> 	  held on the server waiting for them to be requested by libpq.
> 	  One complexity is that a query like SELECT 1/col could error
> 	  out mid-way through the result set.