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* How to interface hash access to user types
@ 1970-01-01 00:00 Wolf-D. Ihlenfeldt <wolf@molout.tutkie.tut.ac.jp>
1994-07-16 02:14 ` Re: How to interface hash access to user types Paul M. Aoki <aoki@CS.Berkeley.EDU>
0 siblings, 1 reply; 2+ messages in thread
From: Wolf-D. Ihlenfeldt @ 1970-01-01 00:00 UTC (permalink / raw)
To: ucb-postgres
he Postgres 4.2 documentation explains in detail
how to interface user data types to btree access methods
but seems to be completely silent about introducing a
hash access method for a user data type. Does anybody
know the necessary steps ?
Details: I need to access unsigned 64 bit integers. I have
a comprehensive set of functions for this type, and I
was able to define a btree access for this type. However,
I always retrieve with the '=' operator and therefore
a hash access to these numbers (which are hashcodes themselves)
might be mor effective. Currently I fail with
WARN:Jul 14 20:30:13:IndexCatalogInformation: no amop 405 65504 1
in the query
(dbxtool) print query
`wb_dbwrite`db_write_prepare`query = "retrieve (Molecules.oid) where Molecules.E_HASHY="5F25E412BAC38683"::uint8"
with an (unprepared) hash index on the E_HASHY field.
Thank you for your help.
WDI
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* Re: How to interface hash access to user types
1970-01-01 00:00 How to interface hash access to user types Wolf-D. Ihlenfeldt <wolf@molout.tutkie.tut.ac.jp>
@ 1994-07-16 02:14 ` Paul M. Aoki <aoki@CS.Berkeley.EDU>
0 siblings, 0 replies; 2+ messages in thread
From: Paul M. Aoki @ 1994-07-16 02:14 UTC (permalink / raw)
To: Wolf-D. Ihlenfeldt <wolf@molout.tutkie.tut.ac.jp>; +Cc: ucb-postgres
wolf@molout.tutkie.tut.ac.jp (Wolf-D. Ihlenfeldt) writes:
> he Postgres 4.2 documentation explains in detail
> how to interface user data types to btree access methods
> but seems to be completely silent about introducing a
> hash access method for a user data type. Does anybody
> know the necessary steps ?
the hash am has only one strategy, which corresponds to "=" (instead
of the five required by btrees).
the hash am needs one "support" function, which corresponds to your
hash function (like btrees, which also have one support function).
once you know that, it shouldn't be too hard to figure out what to do
from the btree instructions and the existing contents of the catalogs..
--
Paul M. Aoki | University of California at Berkeley
aoki@CS.Berkeley.EDU | Dept. of EECS, Computer Science Division (#1776)
| Berkeley, CA 94720-1776
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1970-01-01 00:00 How to interface hash access to user types Wolf-D. Ihlenfeldt <wolf@molout.tutkie.tut.ac.jp>
1994-07-16 02:14 ` Paul M. Aoki <aoki@CS.Berkeley.EDU>
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