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Re: Performance Problems for large inserts into INNODB table via LOAD DATA
Posted by: Rick James
Date: February 28, 2011 11:12AM

"KEY" and "INDEX" are synonyms (in MySQL).
They provide an efficient (usually BTree) mechanism for finding row(s).
"UNIQUE" is an INDEX, plus a uniqueness constraint.
"PRIMARY KEY", in MyISAM is identical in functionality to a UNIQUE KEY. In InnoDB, PRIMARY KEY does that, plus causes the data to be 'clustered'.

-- redundant and wasteful

KEY(x) -- DROP this one
UNIQUE(x) -- keep this one

KEY(x) -- DROP this one
PRIMARY KEY(x) -- keep this one

UNIQUE(x) -- DROP this one
PRIMARY KEY(x) -- keep this one

Probably keep both -- they are different

KEY, INDEX, UNIQUE, PRIMARY KEY -- Each of these provides efficient access to the data.

TicketAttachments -- oops.

innodb_io_capacity = 400 (maybe) for your software RAID.

Only 1-20 rows in a LOAD DATA file -- it works, but is not very efficient.

> I do not see any measurable performance difference whether I use tablespaces or not.
Thanks for supporting my belief. ;)

> Yes, I see performance starts out fast (1000-5000 rows inserted per second), then slows down after about an hour (100-500 rows per second).
That is usually a symptom of some of these:
* "Random" key(s) (not the PK, you say)
* Inadequate value for innodb_buffer_pool_size (but you have a huge buffer_pool)
* Frequent COMMITs (together with certain settings) (but that is not your case)

Even with a lot of random keys, the huge buffer_pool should keep the slowdown from happening for a few hours. If it is coming sooner than that, I don't know the answer.

Hardware RAID, with a "write cache" would probably speed things up by a noticeable factor. (But costly.)

Another note from an older posting: OPTIMIZE TABLE is essentially useless for InnoDB; don't bother using it. It takes a long time, and does not improve space or speed much (except in pathological cases).

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