Re: Single Column Indexes Vs. Multi Column

2008-01-11 Thread Anup Shukla

C.R.Vegelin wrote:

Sebastian,

MySQL uses only one index for searching.
As far as I know this applies to all MySQL versions, right ?



AFAIK, MySQL (atleast from version 5.0 onwards) is capable of
using multiple indexes.

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Anup Shukla

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Regarding MyISAM table locking.

2007-12-27 Thread Anup Shukla

Hi,

From the MySQL manual @ 
http://dev.mysql.com/doc/refman/5.0/en/internal-locking.html


snip
The MyISAM storage engine supports concurrent inserts to reduce 
contention between readers and writers for a given table: If a MyISAM 
table has no free blocks in the middle of the data file, rows are always 
inserted at the end of the data file. In this case, you can freely mix 
concurrent INSERT and SELECT statements for a MyISAM table without 
locks. That is, you can insert rows into a MyISAM table at the same time 
other clients are reading from it.

/snip

I plan to use MySQL to store logs from my web server for later analysis.
Analysis here basically means, that i will be using the data for a lot 
of purposes, which in turn implies that there will be tons of selects 
happening on the data.


From what i understand (as stated in the manual) the web server can 
freely insert log records to the table and my application can freely 
select data from the same tables without worrying about locks, since the 
writes are purely INSERTs and i do not have a need to update.


What i want to understand is, how would things behave if i partition the 
table such that each partition stores only a weeks worth of data.


I plan to do so, because it allows (atleast from my understanding) me to 
easily consolidate a weeks data and then drop the partition, while my 
web server is happily INSERTing logs to the current weeks partition and 
my application is happily SELECTing rows from available partitions and 
everything works without any locking issues.


I would really be thankful if someone could tell me as to how correct 
am i?


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Anup Shukla

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