[TYPO3-dev] improve "alias" indices on UTF8 sites

[Martin Kutschker]

Steffen Kamper schrieb:
> Hi Masi,
> 
> "Martin Kutschker" <Martin.Kutschker at n0spam-blackbox.net> schrieb im 
> Newsbeitrag 
> news:mailman.1.1165235593.14398.typo3-dev at lists.netfielders.de...
> 
>>Hi!
>>
>>Some fields used for indices (eg aliases etc) are known to take only 
>>7bit-singlebyte data, yet Mysql has to deal with potentially 
>>8bit-multibyte data. Do you think that Mysql will access the indices more 
>>efficient if these fields were marked as latin1? I think it may use less 
>>memory for buffers etc.
>>
>>Masi
> 
> 
> is it possible that you think of the 7-byte roll-pointer, which is an 
> additional field of MySQL ?

No. All DBs that support UTF8 natively must allocate more than char-length 
for utf8 as it uses a variable byte length. I think that for performance 
reasons sort buffers use a fixed in-memory length. So this will be three 
times the char length for utf8. This memory is wasted but could be claimed 
for other queries as there is a maximum buffer size. So reducing the buffer 
size for one query will increase the overall performance for parallel queries.

Masi