Re: [Fwd: PREPARE in ECPG]
| От | BTS |
|---|---|
| Тема | Re: [Fwd: PREPARE in ECPG] |
| Дата | |
| Msg-id | Sea1-DAV34i8bWgl6Sp0001d6b5@hotmail.com обсуждение исходный текст |
| Ответ на | [Fwd: PREPARE in ECPG] (Paul Tilles <Paul.Tilles@noaa.gov>) |
| Список | pgsql-interfaces |
Our application consists of several programs with one major running in
online mode. In online mode we start typically 40 to 60 incarnations of this
program, and it runs for months (until the machine is rebooted). Therefor
the effect on an efficient PREPARE/EXECUTE will be significant.
We know the importance of this from running our application under Informix,
because there we use the efficient PREPARE/EXECUTE.
We look forward for the ECPG implementation of
PREPARE plan_name [ (datatype [, ...] ) ] AS query
and
EXECUTE plan_name [ (parameter [, ...] ) ] INTO...
We hope to be able to write statements like:
EXEC SQL
PREPARE stm (char(5), int) as SELECT a,b,c INTO :host_a, :host_b,
:host_c
FROM mytable WHERE d=$1 AND e=$2;
...
EXEC SQL
EXECUTE stm (:host_d, :host_e);
or
EXEC SQL
PREPARE stm (char(5), int) as SELECT a,b,c FROM mytable WHERE d=$1 AND
e=$2;
...
EXEC SQL
EXECUTE stm (:host_d, :host_e) INTO :host_a, :host_b, :host_c;
Best Regards
Bo Tveden
Mads Madsen
BTS Solutions
----- Original Message -----
From: "Bruce Momjian" <pgman@candle.pha.pa.us>
To: "Paul Tilles" <Paul.Tilles@noaa.gov>
Cc: <pgsql-interfaces@postgresql.org>
Sent: Friday, May 23, 2003 5:55 PM
Subject: Re: [Fwd: [INTERFACES] PREPARE in ECPG]
>
> As far as Informix, we do have PREPARE/EXECUTE in 7.3, and 7.4, due out
> in a few months, will have several Informix-specific improvments, like
> better ecpg support (and hance better 4GL support via Aubit 4GL), plus
> SQL improvements like WHERE CURRENT OF and WITH HOLD cursors.
>
> --------------------------------------------------------------------------
-
>
> Paul Tilles wrote:
> >
> >
> > Paul Tilles wrote:
> >
> > > Your posting is very interesting! We are looking at porting our
> > > Informix applications to PostgreSQL due to the increased cost of
> > > licenses.
> > >
> > > I had read in the documentation that PREPARE/EXECUTE is available in
> > > Version 7.3. If this is not the case, we would not be able to port
> > > our applications to PostgreSQL.
> > >
> > > BTW, what version of ecpg do you have (I have version 2.80)?
> > >
> > > Can anybody out there in PostgreSQL-land please comment on this?
> > >
> > > Thanks.
> > >
> > > Paul Tilles
> > >
> > > BTS wrote:
> > >
> > >> We have a large application written in C language (not C++) using
> > >> embedded SQL. The number of tables in the database is about 60, with
> > >> about 80 SQL indexes. Total number of SQL statements is about 800 to
> > >> 1000. All SQL statements are generated by a program generator
> > >> handling the differences between Oracle/Informix/PostgreSQL. All
> > >> SELECT statements are "simple", extracting data from only one table
> > >> (no joins or similar). The application works under Oracle (using
> > >> Pro-C preprocessor) and Informix (using ESQL preprocessor). Under
> > >> PostgreSQL we use the ECPG preprocessor. FYI it took us only a few
> > >> weeks to port the application to PostgreSQL. The application works
> > >> under all these database systems and has been trimmed with the
> > >> necessary SQL indexes etc. For the PostgreSQL we continually run the
> > >> necessary VACUUM + ANALYZE to ensure the PostgreSQL optimizer uses
> > >> the proper SQL indexes (there are no table scans). The documentation
> > >> for PostgreSQL 7.3 explains about introducing the optimized
> > >> PREPARE/EXECUTE statements, but we have discovered this is not
> > >> implemented (yet) in ECPG (we are using release 7.3.2). See comments
> > >> in "ecpg/preproc/preproc.y". We have a major installation currently
> > >> using Oracle, but they want to switch to PostgreSQL when the access
> > >> time reaches a reasonable level. The size of database (tables +
> > >> indexes) is about 120 GB, and the number of SELECTs from the tables
> > >> is of the magnitude 200 to 500 million per day, split over a number
> > >> of SUN E10K machines (about 30 processors each with 1 GB RAM). (The
> > >> Oracle license and annual maintenance fee on this setup are
> > >> exorbitant!!) Without the optimized PREPARE/EXECUTE we see a SELECT
> > >> time of about 30 milliseconds (measured on the SUN E10K) of which
> > >> most seems to be CPU time spent inside postmaster. The similar time
> > >> from Oracle is about 1 to 5 milliseconds on the same hardware. Both
> > >> PostgreSQL and Oracle have been setup with a cache (shared_buffers)
> > >> of 120000. To our customer the 30 milliseconds are not acceptable.
> > >> Based on the PostgreSQL 7.3 documentation we should expect "improved
> > >> performance" when using prepared queries. This leads to a couple of
> > >> questions regarding the optimized PREPARE/EXECUTE: - Do you have any
> > >> indication of the performance improvement (measured in percentage)?
> > >> - When will the optimized PREPARE/EXECUTE be implemented in ECPG?
> > >> Best Regards
> > >> Bo Tveden
> > >> Mads Madsen
> > >> BTS Solutions
> > >
>
> --
> Bruce Momjian | http://candle.pha.pa.us
> pgman@candle.pha.pa.us | (610) 359-1001
> + If your life is a hard drive, | 13 Roberts Road
> + Christ can be your backup. | Newtown Square, Pennsylvania
19073
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Don't 'kill -9' the postmaster
>
online mode. In online mode we start typically 40 to 60 incarnations of this
program, and it runs for months (until the machine is rebooted). Therefor
the effect on an efficient PREPARE/EXECUTE will be significant.
We know the importance of this from running our application under Informix,
because there we use the efficient PREPARE/EXECUTE.
We look forward for the ECPG implementation of
PREPARE plan_name [ (datatype [, ...] ) ] AS query
and
EXECUTE plan_name [ (parameter [, ...] ) ] INTO...
We hope to be able to write statements like:
EXEC SQL
PREPARE stm (char(5), int) as SELECT a,b,c INTO :host_a, :host_b,
:host_c
FROM mytable WHERE d=$1 AND e=$2;
...
EXEC SQL
EXECUTE stm (:host_d, :host_e);
or
EXEC SQL
PREPARE stm (char(5), int) as SELECT a,b,c FROM mytable WHERE d=$1 AND
e=$2;
...
EXEC SQL
EXECUTE stm (:host_d, :host_e) INTO :host_a, :host_b, :host_c;
Best Regards
Bo Tveden
Mads Madsen
BTS Solutions
----- Original Message -----
From: "Bruce Momjian" <pgman@candle.pha.pa.us>
To: "Paul Tilles" <Paul.Tilles@noaa.gov>
Cc: <pgsql-interfaces@postgresql.org>
Sent: Friday, May 23, 2003 5:55 PM
Subject: Re: [Fwd: [INTERFACES] PREPARE in ECPG]
>
> As far as Informix, we do have PREPARE/EXECUTE in 7.3, and 7.4, due out
> in a few months, will have several Informix-specific improvments, like
> better ecpg support (and hance better 4GL support via Aubit 4GL), plus
> SQL improvements like WHERE CURRENT OF and WITH HOLD cursors.
>
> --------------------------------------------------------------------------
-
>
> Paul Tilles wrote:
> >
> >
> > Paul Tilles wrote:
> >
> > > Your posting is very interesting! We are looking at porting our
> > > Informix applications to PostgreSQL due to the increased cost of
> > > licenses.
> > >
> > > I had read in the documentation that PREPARE/EXECUTE is available in
> > > Version 7.3. If this is not the case, we would not be able to port
> > > our applications to PostgreSQL.
> > >
> > > BTW, what version of ecpg do you have (I have version 2.80)?
> > >
> > > Can anybody out there in PostgreSQL-land please comment on this?
> > >
> > > Thanks.
> > >
> > > Paul Tilles
> > >
> > > BTS wrote:
> > >
> > >> We have a large application written in C language (not C++) using
> > >> embedded SQL. The number of tables in the database is about 60, with
> > >> about 80 SQL indexes. Total number of SQL statements is about 800 to
> > >> 1000. All SQL statements are generated by a program generator
> > >> handling the differences between Oracle/Informix/PostgreSQL. All
> > >> SELECT statements are "simple", extracting data from only one table
> > >> (no joins or similar). The application works under Oracle (using
> > >> Pro-C preprocessor) and Informix (using ESQL preprocessor). Under
> > >> PostgreSQL we use the ECPG preprocessor. FYI it took us only a few
> > >> weeks to port the application to PostgreSQL. The application works
> > >> under all these database systems and has been trimmed with the
> > >> necessary SQL indexes etc. For the PostgreSQL we continually run the
> > >> necessary VACUUM + ANALYZE to ensure the PostgreSQL optimizer uses
> > >> the proper SQL indexes (there are no table scans). The documentation
> > >> for PostgreSQL 7.3 explains about introducing the optimized
> > >> PREPARE/EXECUTE statements, but we have discovered this is not
> > >> implemented (yet) in ECPG (we are using release 7.3.2). See comments
> > >> in "ecpg/preproc/preproc.y". We have a major installation currently
> > >> using Oracle, but they want to switch to PostgreSQL when the access
> > >> time reaches a reasonable level. The size of database (tables +
> > >> indexes) is about 120 GB, and the number of SELECTs from the tables
> > >> is of the magnitude 200 to 500 million per day, split over a number
> > >> of SUN E10K machines (about 30 processors each with 1 GB RAM). (The
> > >> Oracle license and annual maintenance fee on this setup are
> > >> exorbitant!!) Without the optimized PREPARE/EXECUTE we see a SELECT
> > >> time of about 30 milliseconds (measured on the SUN E10K) of which
> > >> most seems to be CPU time spent inside postmaster. The similar time
> > >> from Oracle is about 1 to 5 milliseconds on the same hardware. Both
> > >> PostgreSQL and Oracle have been setup with a cache (shared_buffers)
> > >> of 120000. To our customer the 30 milliseconds are not acceptable.
> > >> Based on the PostgreSQL 7.3 documentation we should expect "improved
> > >> performance" when using prepared queries. This leads to a couple of
> > >> questions regarding the optimized PREPARE/EXECUTE: - Do you have any
> > >> indication of the performance improvement (measured in percentage)?
> > >> - When will the optimized PREPARE/EXECUTE be implemented in ECPG?
> > >> Best Regards
> > >> Bo Tveden
> > >> Mads Madsen
> > >> BTS Solutions
> > >
>
> --
> Bruce Momjian | http://candle.pha.pa.us
> pgman@candle.pha.pa.us | (610) 359-1001
> + If your life is a hard drive, | 13 Roberts Road
> + Christ can be your backup. | Newtown Square, Pennsylvania
19073
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Don't 'kill -9' the postmaster
>
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