Hi, Smit! On Mar 17, smit hinsu wrote:
Hi Sergei and Roberto,
My name is Smit Hinsu and I am final year undergrad student. I have good knowledge about database internals and good experience with C++.
I find feature of creating index on BLOB quickly using MD-5 interesting. I have understood basic requirements for this feature. I have following questions in my mind currently.
I think, HASH index is not supported in MySQL's version of MyISAM storage engine. Has MariaDB removed this restriction?
No, it is not supported in MariaDB either. I mean, neither in MySQL nor in MariaDB you can write CREATE TABLE (.... INDEX (...) USING HASH...) ENGINE=MyISAM This doesn't work. But both in MySQL and in MariaDB, MyISAM actually supports these indexes! They are not available to the SQL user, but they are there in the code. This task, precisely, is to provide SQL access to this feature.
We should support index for BLOB for BTREE index also in which we store only hash value of the value in BTREE. Is this possible?
That's what MyISAM does, yes.
Can you suggest me some startup task related to index or storage engine which can make me familiar with the related parts? I have started to look at code.
Look in storage/myisam for "MI_UNIQUEDEF" - see where this structure is used and how. Regards, Sergei