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Re: Query ResultSet parsing speedup patch (resend)

From: Dave Cramer <pg(at)fastcrypt(dot)com>
To: Mikko Tiihonen <mikko(dot)tiihonen(at)iki(dot)fi>
Cc: pgsql-jdbc(at)postgresql(dot)org
Subject: Re: Query ResultSet parsing speedup patch (resend)
Date: 2006-10-01 14:15:03
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-jdbc
On 29-Sep-06, at 6:01 PM, Mikko Tiihonen wrote:

> Hi,
> This is a resend since I did not get any feedback to this patch when I
> sent it two months ago. Could someone at least have some  
> recommendations
> what I should do to get this patch evaluated or even applied to the
> official source.
> Also, could someone update the CVS info page
> ( to point to the new
> pgfoundry ?
Well, we haven't actually moved it yet, it's there more by accident.
> ---
> I tried to optimise the parsing of ResultSets from the network stream,
> especially int and long values, but also a bit for String values.
> The attached patch gives upto 40% speedup when parsing larger queries
> containing equal amounts of int4, int8 or varchar(16) columns if the
> system is cpu bound. The speedup comes mainly from avoiding  
> creation of
> useless objects and avoiding useless byte[] copies. In more real-life
> scenarios the speedup will be much smaller.
> The patch also contains the test code which I used to test the
> performance ( The benchmark results are:
> unpatched 503 jdbc driver: speed: 180.18  memory: 36.8MB
> patched 503 jdbc driver:   speed: 261.44  memory: 19.6MB
>                                   +40%            -40%
> The benchmark was run on Java6rc build 100 with postgresql 8.1.4  
> running
> on localhost with Athlon64 2x2GHz, 64bit mode.
> If the patch is accepted I can try to do similar optimisations for  
> other
> fields.
> ---
> What the patch does:
> Parsing string:
> old way: read byte[] containing the exact bytes of a string
> new way: create a string directly from network buffer with start  
> and end
> index
> Parsing numbers:
> old way: create a string that contains the number and use
> Integer.parseInt
> new way: parse the number directly from bytes
> Exact changes explained:
> new class VisibleBufferedInputStream:
> - replaced with faster implementation
>   * no synchronisation
>   * allows direct access to the buffer byte[] contents which helps
>     to avoiding useless copies when converting to String
>   * has method for scanning the length of next null terminated string
> PGStream:
> - uses VisibleBuffereInputStream
>   * faster implementations for for ReceiveIntegerR and ReceiveString
> AbstractJdbc2ResultSet
> -  parses int and long values directly from byte[] -> number instead
>    of first creating a throw-away string
> -  if the fast conversion fails or if the current charset is not safe
>    for the optimisation then uses the old way to parse
> -  also very minor optimisation to getFixedString to optimise for
>    non-money string types
> Encoding:
> -  uses HashMap instead of synchronised Hashtable
> -  does not do two queries to encodings map when obtaining database
>    encoding
> -  added method to check if the numbers match ASCII charset locations
>    (all currently listed charsets match)
> <postgresql-resultset-parsing-speedup.patch>
> ---------------------------(end of  
> broadcast)---------------------------
> TIP 5: don't forget to increase your free space map settings

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