Обсуждение: Significance of the magic number of btree pages..?

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Significance of the magic number of btree pages..?

От
Anil Kumar
Дата:
Hi to All,
Iam new to the group and to postgresql. Currently Iam trying to understand how does the planner work by using gdb. During the execution of a plan I observed a variable "BTREE_MAGIC" which is defined 0x053162 and called, 'the magic number of btree pages'. I couldnt understand the concept behind the 'magic number' and the "0x053162". Can anyone kindly explain the significance of the 'magic number of btree pages' or refer to some document where I can get idea about this.

Thanks in Advance,
Anil


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Re: Significance of the magic number of btree pages..?

От
Heikki Linnakangas
Дата:
Anil Kumar wrote:
> Hi to All,
> Iam new to the group and to postgresql. Currently Iam trying to understand how does the planner work by using gdb.
Duringthe execution of a plan I observed a variable "BTREE_MAGIC" which is defined 0x053162 and called, 'the magic
numberof btree pages'. I couldnt understand the concept behind the 'magic number' and the "0x053162". Can anyone kindly
explainthe significance of the 'magic number of btree pages' or refer to some document where I can get idea about this.


It's just a sanity check and a debugging aid, to let you check that a 
b-tree metapage is indeed a b-tree metapage.

--   Heikki Linnakangas  EnterpriseDB   http://www.enterprisedb.com