| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Jan Wieck <JanWieck(at)Yahoo(dot)com> |
| Cc: | Scott Cain <cain(at)cshl(dot)org>, PgSQL Performance ML <pgsql-performance(at)postgresql(dot)org>, pgsql-sql(at)postgresql(dot)org |
| Subject: | Re: [SQL] EXTERNAL storage and substring on long strings |
| Date: | 2003-08-14 18:00:21 |
| Message-ID: | 6311.1060884021@sss.pgh.pa.us |
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| Lists: | pgsql-performance pgsql-sql |
Jan Wieck <JanWieck(at)Yahoo(dot)com> writes:
> Doesn't look that unrealistic to me. A plain text based substring
> function will reassemble the whole beast first before cutting out the
> wanted part. His manually chunked version will read only those chunks
> needed.
So does substr(), if applied to EXTERNAL (non-compressed) toasted text.
See John Gray's improvements a release or two back.
regards, tom lane
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