INDEX_MAX_KEYS

Started by Greg Copelandalmost 24 years ago8 messages
#1Greg Copeland
greg@CopelandConsulting.Net

I'm looking through the index code and just happened to notice that
INDEX_MAX_KEYS is currently set to 16. It there a reason for this value
to be at 16 or was it arbitrarily specified?

Curious,
Greg

#2Bruce Momjian
pgman@candle.pha.pa.us
In reply to: Greg Copeland (#1)
Re: INDEX_MAX_KEYS

Greg Copeland wrote:

Checking application/pgp-signature: FAILURE
-- Start of PGP signed section.

I'm looking through the index code and just happened to notice that
INDEX_MAX_KEYS is currently set to 16. It there a reason for this value
to be at 16 or was it arbitrarily specified?

Arbitrary, and there is discussion about increasing it.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026
#3Jan Wieck
janwieck@yahoo.com
In reply to: Bruce Momjian (#2)
Re: INDEX_MAX_KEYS

Bruce Momjian wrote:

Greg Copeland wrote:

Checking application/pgp-signature: FAILURE
-- Start of PGP signed section.

I'm looking through the index code and just happened to notice that
INDEX_MAX_KEYS is currently set to 16. It there a reason for this value
to be at 16 or was it arbitrarily specified?

Arbitrary, and there is discussion about increasing it.

Wasn't it that this number had to be <= the maximum number of
function args?

Jan

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#4Bruce Momjian
pgman@candle.pha.pa.us
In reply to: Jan Wieck (#3)
Re: INDEX_MAX_KEYS

Jan Wieck wrote:

Bruce Momjian wrote:

Greg Copeland wrote:

Checking application/pgp-signature: FAILURE
-- Start of PGP signed section.

I'm looking through the index code and just happened to notice that
INDEX_MAX_KEYS is currently set to 16. It there a reason for this value
to be at 16 or was it arbitrarily specified?

Arbitrary, and there is discussion about increasing it.

Wasn't it that this number had to be <= the maximum number of
function args?

Yes, they are related. At least I think so. Anyway, the parameter that
needs increasing is max function args. I got mixed up there.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026
#5Jan Wieck
janwieck@yahoo.com
In reply to: Bruce Momjian (#4)
Re: INDEX_MAX_KEYS

Bruce Momjian wrote:

Jan Wieck wrote:

Bruce Momjian wrote:

Greg Copeland wrote:

Checking application/pgp-signature: FAILURE
-- Start of PGP signed section.

I'm looking through the index code and just happened to notice that
INDEX_MAX_KEYS is currently set to 16. It there a reason for this value
to be at 16 or was it arbitrarily specified?

Arbitrary, and there is discussion about increasing it.

Wasn't it that this number had to be <= the maximum number of
function args?

Yes, they are related. At least I think so. Anyway, the parameter that
needs increasing is max function args. I got mixed up there.

Then again, if they are related, why not let the index max
keys be automatically set according to the function max arg
configuration? Is there any reason someone want's to limit
it smaller than the system could technically handle?

Jan

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#================================================== JanWieck@Yahoo.com #

_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com

#6Bruce Momjian
pgman@candle.pha.pa.us
In reply to: Jan Wieck (#5)
Re: INDEX_MAX_KEYS

Jan Wieck wrote:

Arbitrary, and there is discussion about increasing it.

Wasn't it that this number had to be <= the maximum number of
function args?

Yes, they are related. At least I think so. Anyway, the parameter that
needs increasing is max function args. I got mixed up there.

Then again, if they are related, why not let the index max
keys be automatically set according to the function max arg
configuration? Is there any reason someone want's to limit
it smaller than the system could technically handle?

I don't think so. I don't remember if there is a NULL bitmap that is
fixed length for indexes. I don't think so.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026
#7Tom Lane
tgl@sss.pgh.pa.us
In reply to: Bruce Momjian (#4)
Re: INDEX_MAX_KEYS

Bruce Momjian <pgman@candle.pha.pa.us> writes:

Wasn't it that this number had to be <= the maximum number of
function args?

Yes, they are related. At least I think so.

They have to be exactly the same, because both are tied to the size
of the oidvector type.

regards, tom lane

#8Bruce Momjian
pgman@candle.pha.pa.us
In reply to: Tom Lane (#7)
Re: INDEX_MAX_KEYS

Tom Lane wrote:

Bruce Momjian <pgman@candle.pha.pa.us> writes:

Wasn't it that this number had to be <= the maximum number of
function args?

Yes, they are related. At least I think so.

They have to be exactly the same, because both are tied to the size
of the oidvector type.

And because oidvector has to be a fixed length, we are have overhead in
increasing it?

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026