The initial implementation of pg_dump's --section option supposed that the
existing --schema-only and --data-only options could be made equivalent to
--section settings. This is wrong, though, due to dubious but long since
set-in-stone decisions about where to dump SEQUENCE SET items, as seen in
bug report from Martin Pitt. (And I'm not totally convinced there weren't
other bugs, either.) Undo that coupling and instead drive --section
filtering off current-section state tracked as we scan through the TOC
list to call _tocEntryRequired().
To make sure those decisions don't shift around and hopefully save a few
cycles, run _tocEntryRequired() only once per TOC entry and save the result
in a new TOC field. This required minor rejiggering of ACL handling but
also allows a far cleaner implementation of inhibit_data_for_failed_table.
Also, to ensure that pg_dump and pg_restore have the same behavior with
respect to the --section switches, add _tocEntryRequired() filtering to
WriteToc() and WriteDataChunks(), rather than trying to implement section
filtering in an entirely orthogonal way in dumpDumpableObject(). This
required adjusting the handling of the special ENCODING and STDSTRINGS
items, but they were pretty weird before anyway.
Minor other code review for the patch, too.
This patch fixes three places (which AFAICT is all of them) where runtime
was O(N^2) in the number of TOC entries, by using an index array to replace
linear searches of the TOC list. This performance issue is a bit less bad
than those recently fixed, because it depends on the number of items dumped
not the number in the source database, so the problem can be dodged by
doing partial dumps.
The previous coding already had an instance of one of the two index arrays
needed, but it was only calculated in parallel-restore cases; now we need
it all the time. I also chose to move the arrays into the ArchiveHandle
data structure, to make this code a bit more ready for the day that we
try to sling multiple ArchiveHandles around in pg_dump or pg_restore.
Since we still need some server-side work before pg_dump can really cope
nicely with tens of thousands of tables, there's probably little point in
back-patching.
The old code was using exit_horribly or die_horribly other depending on
whether it had an ArchiveHandle on which to close the connection or not;
but there were places that were passing a NULL ArchiveHandle to
die_horribly, and other places that used exit_horribly while having an
AH available. So there wasn't all that much consistency.
Improve the situation by keeping only one of the routines, and instead
of having to pass the AH down from the caller, arrange for it to be
present for an on_exit_nicely callback to operate on.
Author: Joachim Wieland
Some tweaks by me
Per a suggestion from Robert Haas, in the ongoing "parallel pg_dump"
saga.
This was for demonstration only, and now it was creating compiler
warnings from zlib without an obvious fix (see also
d923125b77), let's just remove it. The
"directory" format is presumably similar enough anyway.
This is another round of refactoring to make things simpler for parallel
pg_dump. pg_dump.c now issues SQL queries through the relevant Archive
object, rather than relying on the global variable g_conn. This commit
isn't quite enough to get rid of g_conn entirely, but it makes a big
dent in its utilization and, along the way, manages to be slightly less
code than before.
In commit 6545a901aa, I removed the mini SQL
lexer that was in pg_backup_db.c, thinking that it had no real purpose
beyond separating COPY data from SQL commands, which purpose had been
obsoleted by long-ago fixes in pg_dump's archive file format.
Unfortunately this was in error: that code was also used to identify
command boundaries in INSERT-style table data, which is run together as a
single string in the archive file for better compressibility. As a result,
direct-to-database restores from archive files made with --inserts or
--column-inserts fail in our latest releases, as reported by Dick Visser.
To fix, restore the mini SQL lexer, but simplify it by adjusting the
calling logic so that it's only required to cope with INSERT-style table
data, not arbitrary SQL commands. This allows us to not have to deal with
SQL comments, E'' strings, or dollar-quoted strings, none of which have
ever been emitted by dumpTableData_insert.
Also, fix the lexer to cope with standard-conforming strings, which was the
actual bug that the previous patch was meant to solve.
Back-patch to all supported branches. The previous patch went back to 8.2,
which unfortunately means that the EOL release of 8.2 contains this bug,
but I don't think we're doing another 8.2 release just because of that.
Valid values are --pre-data, data and post-data. The option can be
given more than once. --schema-only is equivalent to
--section=pre-data --section=post-data. --data-only is equivalent
to --section=data.
Andrew Dunstan, reviewed by Joachim Wieland and Josh Berkus.
pg_backup_db.c contained a mini SQL lexer with which it tried to identify
boundaries between SQL commands, but that code was not designed to cope
with standard_conforming_strings, and would get the wrong answer if a
backslash immediately precedes a closing single quote in such a string,
as per report from Julian Mehnle. The bug only affects direct-to-database
restores from archive files made with standard_conforming_strings = on.
Rather than complicating the code some more to try to fix that, let's just
rip it all out. The only reason it was needed was to cope with COPY data
embedded into ordinary archive entries, which was a layout that was used
only for about the first three weeks of the archive format's existence,
and never in any production release of pg_dump. Instead, just rely on the
archive file layout to tell us whether we're printing COPY data or not.
This bug represents a data corruption hazard in all releases in which
standard_conforming_strings can be turned on, ie 8.2 and later, so
back-patch to all supported branches.
The style is set to "printf" for backwards compatibility everywhere except
on Windows, where it is set to "gnu_printf", which eliminates hundreds of
false error messages from modern versions of gcc arising from %m and %ll{d,u}
formats.
It appears that gcc 4.5 can issue such warnings for whole structs, not
just scalar variables as in the past. Refactor some pg_dump code slightly
so that the OutputContext local variables are always initialized, even
if they won't be used. It's cheap enough to not be worth worrying about.
With hundreds of thousands of TOC entries, the repeated searches in
reduce_dependencies() become the dominant cost. Get rid of that searching
by constructing reverse-dependency lists, which we can do in O(N) time
during the fix_dependencies() preprocessing. I chose to store the reverse
dependencies as DumpId arrays for consistency with the forward-dependency
representation, and keep the previously-transient tocsByDumpId[] array
around to locate actual TOC entry structs quickly from dump IDs.
While this fixes the slow case reported by Vlad Arkhipov, there is still
a potential for O(N^2) behavior with sufficiently many tables:
fix_dependencies itself, as well as mark_create_done and
inhibit_data_for_failed_table, are doing repeated searches to deal with
table-to-table-data dependencies. Possibly this work could be extended
to deal with that, although the latter two functions are also used in
non-parallel restore where we currently don't run fix_dependencies.
Another TODO is that we fail to parallelize restore of multiple blobs
at all. This appears to require changes in the archive format to fix.
Back-patch to 9.0 where the problem was reported. 8.4 has potential issues
as well; but since it doesn't create a separate TOC entry for each blob,
it's at much less risk of having enough TOC entries to cause real problems.
to make it easier to reuse that code. There is no user-visible changes.
This is in preparation for the patch to add a new archive format, a directory,
to perform a custom-like dump but with each table being dumped to a separate
file (that in turn is a prerequisite for parallel pg_dump). This also makes it
easier to add new compression methods in the future, and makes the
pg_backup_custom.c code easier to read, when the compression-related code is
factored out.
Joachim Wieland, with heavy editorialization by me.
a separate archive entry for each BLOB, and use pg_dump's standard methods
for dealing with its ownership, ACL if any, and comment if any. This means
that switches like --no-owner and --no-privileges do what they're supposed
to. Preliminary testing says that performance is still reasonable even
with many blobs, though we'll have to see how that shakes out in the field.
KaiGai Kohei, revised by me
two new lists, rather than repeatedly rescanning the main TOC list.
This avoids a potential O(N^2) slowdown, although you'd need a *lot*
of tables to make that really significant; and it might simplify future
improvements in the scheduling algorithm by making the set of ready
items more easily inspectable. The original thought that it would
in itself result in a more efficient job dispatch order doesn't seem
to have been borne out in testing, but it seems worth doing anyway.
The previous implementation got it right in most cases but failed in one:
if you pg_dump into an archive with standard_conforming_strings enabled, then
pg_restore to a script file (not directly to a database), the script will set
standard_conforming_strings = on but then emit large object data as
nonstandardly-escaped strings.
At the moment the code is made to emit hex-format bytea strings when dumping
to a script file. We might want to change to old-style escaping for backwards
compatibility, but that would be slower and bulkier. If we do, it's just a
matter of reimplementing appendByteaLiteral().
This has been broken for a long time, but given the lack of field complaints
I'm not going to worry about back-patching.
post-data step is run in a separate worker child (a thread on Windows, a child
process elsewhere) up to the concurrent number specified by the new pg_restore
command-line --multi-thread | -m switch.
Andrew Dunstan, with some editing by Tom Lane.
and standard_conforming_strings; likewise for the other client programs
that need it. As per previous discussion, a pg_dump dump now conforms
to the standard_conforming_strings setting of the source database.
We don't use E'' syntax in the dump, thereby improving portability of
the SQL. I added a SET escape_strings_warning = off command to keep
the dumps from getting a lot of back-chatter from that.
> found in a pg_dump archive. It had problems with dollar-quote tags
broken across bufferload boundaries (this may explain bug report from
Rod Taylor), also with dollar-quote literals of the form $a$a$...,
and was also confused about the rules for backslash in double quoted
identifiers (ie, they're not special). Also put in placeholder support
for E'...' literals --- this will need more work later.
using the recently added lo_create() function. The restore logic in
pg_restore is greatly simplified as well, since there's no need anymore
to try to adjust database references to match a new set of blob OIDs.
multiline command or to rerun the command easily later.
Whereas displaying the failed SQL command is a matter of fixing the
error
messages.
The latter is complicated by failed COPY commands which, with
die-on-errors
off, results in the data being processed as a command, so dumping the
command will dump all of the data.
In the case of long commands, should the whole command be dumped? eg.
(eg.
several pages of function definition).
In the case of the COPY command, I'm not sure what to do. Obviously, it
would be best to avoid sending the data, but the data and command are
combined (from memory). Also, the 'data' may be in the form of INSERT
statements.
Attached patch produces the first 125 chars of the command:
pg_restore: [archiver (db)] Error while PROCESSING TOC:
pg_restore: [archiver (db)] Error from TOC Entry 26; 1255 16449270
FUNCTION
plpgsql_call_handler() pjw
pg_restore: [archiver (db)] could not execute query: ERROR: function
"plpgsql_call_handler" already exists with same argument types
Command was: CREATE FUNCTION plpgsql_call_handler() RETURNS
language_handler
AS '/var/lib/pgsql-8.0b1/lib/plpgsql', 'plpgsql_call_han...
pg_restore: [archiver (db)] Error from TOC Entry 27; 1255 16449271
FUNCTION
plpgsql_validator(oid) pjw
pg_restore: [archiver (db)] could not execute query: ERROR: function
"plpgsql_validator" already exists with same argument types
Command was: CREATE FUNCTION plpgsql_validator(oid) RETURNS void
AS '/var/lib/pgsql-8.0b1/lib/plpgsql', 'plpgsql_validator'
LANGU...
Philip Warner
will treat any unquoted string that starts with a $ and has no preceding
identifier chars as a potential $-quote tag, it then makes sure that the
tag chars are valid. If so, it processes the $-quote.
Philip Warner
errors. This is the second submission, which integrates Tom comments about
localisation and exit code. I also added some comments about one sql
command which is not ignored.
Fabien COELHO
WITH/WITHOUT OIDS in dump files. This makes dump files more portable.
I have updated the pg_dump version so old binary dumps will load fine.
Pre-7.5 dumps use WITHOUT OIDS in SQL were needed, so they should be
fine.
any restore operation, thereby ensuring that dumped data is interpreted
the same way it was dumped even if the target database has a different
encoding. Per suggestions from Pavel Stehule and others. Also,
simplify scheme for handling check_function_bodies ... we may as well
just set that at the head of the script.
Tom Lane
Alvaro Herrera
Peter Eisentraut
Robert Haas
Andrew Dunstan
Bruce Momjian
Heikki Linnakangas
Magnus Hagander
Itagaki Takahiro
Neil Conway