Notiziario settimanale PostgreSQL – 12 luglio 2009

(Traduzione parziale in lingua italiana delle PostgreSQL Weekly News a cura di Gianni Ciolli

Ci sono ancora dei posti per il PgDay San Jose che si terrà domenica 19 luglio. Registratevi!

Grazie a Robert Haas, Brendan Jurd, et al. adesso c’è un nuovo strumento per le commitfest.

Novità sul prodotto PostgreSQL

Rilasciata la versione 2.9.2 di check_postgres, un plugin Nagios per il monitoraggio di PostgreSQL.

Il PostgreSQL RPM Building Project ha rilasciato il PostgreSQL 8.4 Live CD:

Rilasciata la versione 1.3.1 di pgbouncer, un pooler di connessioni per PostgreSQL.

Offerte di lavoro su PostgreSQL per luglio 2009

Notizie locali su PostgreSQL

Il pgDay di San Jose (USA) si terrà domenica 19 luglio 2009, dando il via ad OSCON. Iscrivetevi qui:

Nei giorni 22 e 23 agosto 2009, a St. Augustin, in Germania, vicino a Bonn e Colonia, si terrà OpenSQL Camp. La scadenza per presentare comunicazioni è il 19 luglio 2009. Inviate le vostre proposte!

Domenica 23 agosto 2009 il PostgreSQL User Group tedesco avrà una dev room a FrOSCon. È aperto il Call for Papers:

PyCon Argentina si terrà in Buenos Aires nei giorni 4 e 5 settembre 2009.

Andreas (ads) Scherbaum terrà un corso "PostgreSQL for Corporate Use" al centro di formazione per adulti in Magdeburgo, Germania, dal 7 all’11 settembre 2009. Trovate i dettagli qua:

Si terrà una conferenza in Athens, Georgia, USA il 19 settembre 2009. È aperto il CfP.

Si terrà una conferenza a Seattle, Washington, USA nei giorni 16-18 ottobre 2009. È aperto il CfP.

È aperto il CfP per PGCon Brazil, che si svolgerà Il 23 e 24 ottobre 2009 presso Unicamp, nella città di Campinas, stato di San Paolo.

Il PGDay.EU 2009 si terrà a Telecom ParisTech in Parigi nei giorni 6 e 7 novembre 2009.

Gli organizzatori della conferenza per il decimo anniversario di JPUG stanno accettando proposte. La conferenza si terrà i giorni 20 e 21 novembre 2009 a Tokio.

Rassegna stampa su PostgreSQL

Planet PostgreSQL:

Questo notiziario settimanale PostgreSQL è stato realizzato da David Fetter, Josh Berkus e Devrim GUNDUZ; traduzione parziale in lingua italiana a cura di Gianni Ciolli.

Notizie o annunci destinati a questo notiziario dovranno pervenire entro la mezzanotte di domenica (le 15 nel fuso orario della California). I comunicati in lingua italiana dovranno essere inviati a; per le lingue inglese o tedesca, si scriva rispettivamente a o a

Patch applicate

Peter Eisentraut committed:

  • In pgsql/src/bin/psql/describe.c, show definition of index columns in d on index. This adds a column called "Definition" to the output of psql d on an index, which shows the full expression behind the index column. For indexes on plain columns, this is redundant, but for expression indexes, this reveals the real expression. Author: Khee Chin.

  • More sensible character_octet_length. For character types with typmod, character_octet_length columns in the information schema now show the maximum character length times the maximum length of a character in the server encoding, instead of some huge value as before.

  • In pgsql/src/bin/psql/describe.c, sort child tables by name instead of OID in d+ display. This was an oversight in the recent patch. Found by Tom Lane.

  • In pgsql/src/bin/psql/describe.c, psql backward compatibility fix. For servers older than 8.3, sort display of child tables by relname instead of oid::regclass::text, because the cast from regclass to text did not work back then. The older display may be slightly worse when different schemas are involved, but that should be rare enough.

  • In pgsql/src/makefiles/, when calling unsupported "make check" with a pgxs module, return a nonzero exit code.

  • In pgsql/doc/src/sgml/acronyms.sgml, correct what ISO stands for.

  • Alter some gratuitous uses of "ANSI" when "SQL standard" might have been meant or the reference to a standard was unnecessary.

Tom Lane committed:

  • Fix set_append_rel_pathlist() to deal intelligently with cases where substituting a child rel’s output expressions into the appendrel’s restriction clauses yields a pseudoconstant restriction. We might be able to skip scanning that child rel entirely (if we get constant FALSE), or generate a one-time filter. 8.3 more or less accidentally generated plans that weren’t completely stupid in these cases, but that was only because an extra recursive level of subquery_planner() always occurred and allowed const-simplification to happen. 8.4’s ability to pull up appendrel members with non-Var outputs exposes the fact that we need to work harder here. Per gripe from Sergey Burladyan.

  • In pgsql/src/backend/utils/adt/timestamp.c, use floor() not rint() when reducing precision of fractional seconds in timestamp_trunc, timestamptz_trunc, and interval_trunc(). This change only affects the float-datetime case; the integer-datetime case already behaved like truncation instead of rounding. Per gripe from Mario Splivalo. This is a pre-existing issue but I’m choosing not to backpatch, because it’s such a corner case and there have not been prior complaints. The issue is largely moot anyway given the trend towards integer datetimes.

  • In pgsql/src/bin/psql/describe.c, code review for patch to show definition of index columns in d on index. Safely schema-qualify the pg_get_indexdef call, make the query a bit prettier in -E mode, remove useless join to pg_index, make it more obvious that the header[] array is not overrun.

  • In pgsql/src/include/catalog/pg_proc.h, fix typo in comment.

  • In pgsql/src/backend/catalog/information_schema.sql, query in SQL function still not schema-safe; add a couple more pg_catalog. qualifications.

  • In pgsql/src/backend/utils/mb/mbutils.c, don’t use ‘return’ where you should use ‘PG_RETURN_xxx’.

  • In pgsql/src/bin/psql/describe.c, just a little more schema-qualification …

  • In pgsql/doc/src/sgml/datatype.sgml, add missing HOUR TO SECOND option to list of possible INTERVAL field sets, as noted by Sebastien Flaesch. Also update the claim that we simply throw away fields outside this set — that got changed later to only discard less-significant fields.

  • In pgsql/src/backend/postmaster/postmaster.c, remove no-longer-necessary transmission of postmaster’s LC_COLLATE and LC_CTYPE settings to children via BackendParameters. Per discussion, the postmaster is now just using system defaults anyway, so we might as well save a few cycles during backend startup.

  • In pgsql/contrib/xml2/xslt_proc.c, fix xslt_process() to ensure that it inserts a NULL terminator after the last pair of parameter name/value strings, even when there are MAXPARAMS of them. Aboriginal bug in contrib/xml2, noted while studying bug #4912 (though I’m not sure whether there’s something else involved in that report). This might be thought a security issue, since it’s a potential backend crash; but considering that untrustworthy users shouldn’t be allowed to get their hands on xslt_process() anyway, it’s probably not worth getting excited about.

  • In pgsql/src/backend/optimizer/path/costsize.c, fix set_rel_width() to do something reasonable with non-Var items in a RelOptInfo targetlist. It used to be that the only possibility other than a Var was a RowExpr representing a whole-row child Var, but as of 8.4’s expanded ability to flatten appendrel members, we can get arbitrary expressions in there. Use the expression’s type info and get_typavgwidth() to produce an at-least-marginally-sane result. Note that get_typavgwidth()’s fallback estimate (32 bytes) is the same as what was here before, so there will be no behavioral change for RowExprs. Noted while looking at recent gripe about constant quals pushed down to FunctionScan appendrel members … not only were we failing to recognize the constant qual, we were getting the width estimate wrong :-(

  • Move some declarations in the raw-parser header files to create a clearer distinction between the external API (parser.h) and declarations that only need to be visible within the raw parser code (gramparse.h, which now is only included by parser.c, gram.y, scan.l, and keywords.c). This is in preparation for the upcoming change to a reentrant lexer, which will require referencing YYSTYPE in the declarations of base_yylex and filtered_base_yylex, hence gram.h will have to be included by gramparse.h. We don’t want any more files than absolutely necessary to depend on gram.h, so some cleanup is called for.

  • Fix up PGDLLIMPORT marking for standard_conforming_strings. Moving it into a header file that plpgsql’s scan.l can see broke the previous kluge. Per buildfarm results.

  • Advance the minimum required version of "flex" from 2.5.4 to 2.5.31, and update documentation accordingly. This is required in order to have support for a reentrant scanner. I’m committing this bit separately in order to have an easy reference if we later decide to make the minimum something different (like 2.5.33).

  • Convert the core lexer and parser into fully reentrant code, by making use of features added to flex and bison since this code was originally written. This change doesn’t in itself offer any new capability, but it’s needed infrastructure for planned improvements in plpgsql. Another feature now available in flex is the ability to make it use palloc instead of malloc, so do that to avoid possible memory leaks. (We should at some point change the other lexers likewise, but this commit doesn’t touch them.)

  • In pgsql/src/backend/parser/scan.l, although the flex documentation avers that yyalloc and yyrealloc take size_t arguments, the emitted scanner actually prototypes them with type yy_size_t, which is sometimes not the same thing depending on flex version and platform. Easiest fix seems to be to use yy_size_t. Per buildfarm results.

  • Make the configure messages rejecting old bison and flex versions include the full path and version of the program being rejected.

Heikki Linnakangas committed:

  • In pgsql/src/backend/utils/adt/formatting.c, fix ancient bug in handling of to_char modifier ‘TH’, when used with Hitoshi Harada. In what seems like an oversight, we used to treat ‘TH’ the same as lowercase ‘th’, but only with HH/HH12.

  • In pgsql/src/backend/utils/init/postinit.c, need to use pg_perm_setlocale when setting LC_CTYPE and LC_COLLATE at startup. Otherwise, the LC_CTYPE/COLLATE setting gets reverted when using plperl, which leads to incorrect query results and index corruption. This was accidentally broken in the per-database locale patch in 8.4. Pointed out by Andrew (RhodiumToad) Gierth.

Bruce Momjian committed:

  • Stamp minor library version numbers for 8.5; sorry for the delay.

Patch rifiutate (per adesso)

No one was disappointed this week :-)

Patch in coda

Fujii Masao sent a WIP patch to introduce a new value, sync_file_range, to wal_sync_method.

Heikki Linnakangas sent in a WIP patch to set client_encoding automatically from locale in libpq.

Pavel Stehule sent in a patch to fix BUG #4907: stored procedures and changed tables.

ITAGAKI Takahiro sent in two patches to parallelize pgbench.

Robert Haas sent in three patches to help fix the issue around the *_collapse_limit GUC parameters.

Josh Tolley sent in a patch against the Commitfest code to keep Perl::Critic quiet.

Peter Eisentraut sent in two revisions of a patch to allow byteas to be escaped for input and output as hex.

KaiGai Kohei sent in another revision of his SE-PostgreSQL patches.

Brendan Jurd sent in another revision of the patch to add scientific notation to to_char().

Bernd Helmle sent in another revision of a patch to allow for dropping columns and constraints conditionally.

Tom Lane sent in a patch to increase the minimum flex version in order to enable a reentrant parser.

Dean Rasheed sent in two WIP patches to allow deferrable unique constraints.

Marko (johto) Tiikkaja sent in a patch to allow INSERT…RETURNING inside a CTE.

Andrew (RhodiumToad) Gierth sent in a patch to update hstore to CVS TIP.

Teodor Sigaev sent in a patch to fix wrong algorithms for "contains" and "overlaps" operations over polygons, including regression tests for same.

Jaime Casanova sent in an update to Mark Kirkwood’s patch which adds lock wait statistics to the pg_catalog, including a new view.

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