Posted by peter |
…over 30 millions of rows. “val”
column in this
table has 10000 distinct value, … range scan by index:
mysql>
select count(pad)
from large;
+————+
| count(pad) |… problems solved just doing so. Use
multiple servers to host portions of data …
Posted by peter |
…which covers
multiple columns:
Q1
SELECT sum(length(val))
FROM T…dev/null
In the result
table I compute per query results…of low cardinality even though
MySQL can’t use index well…on high cardinality
tables to show what
difference large BETWEEN can…
Posted by peter |
… as it looks at stats
from different indexes independently not trying … merge works much better than
multiple column indexes. This is in …a full
table scan:
mysql [localhost] {msandbox} (test) > explain
select avg…P.S The tests were done in
MySQL 5.4.2…
Posted by peter |
…do them.
So if you have
table people with KEY(age,zip)… only be able to use
multiple keyparts if first keyparts matched …
differ in these cases:
mysql>
SELECT sql_no_cache name
FROM … this approach when first key
column is not in where clause …
Posted by peter |
… have the task of storing
multiple of boolean values (yes/now…can see for MyISAM 10
columns take just 7 bytes – less…Lets see how these 3
different table format look in Innodb…Null-Aware comparison operator:
mysql>
select count(*)
from cbool where c1NULL…
Posted by
peter @ 11:25 pm ::
Innodb ::
Posted by peter |
… some limits as you can’t use
mysql_num_rows() and…run
mysql_query ,
mysql_fetch_row simply reads data
from memory…be more efficient especially when
multiple servers are involved and you…INSERT …
SELECT to the temporary
table with auto_increment
column and…
Posted by peter |
… LIMIT
Sphinx
mysql>
select forum_id as f
from sptest order … Sphinx adds couple of extra
columns to result set even if …Also note the result set
difference – Sphinx finds no rows and …its ability to scale almost linearly using
multiple CPU cores and…
Posted by
peter @ 10:34 pm ::
sphinx ::
Posted by peter |
… rewrite software to store
multiple users per
table it is best …
columns and create post123 as view:
create view post123 as
select…not be available even if
MySQL would support triggers on VIEWs…have them going to the
different table (typically would be very…
Posted by peter |
… rare category large portion of
table may be scanned to find … to simple
MySQL using
multiple indexes on most
selective columns would … In this case first two
columns from the index can be … well but there are some
differences. I should write another article…
Posted by Hugo Rafael |
… on a web project using
MySql, Apache and Php.
The database has…, 6 in total).
SELECTing data
from the
tables is not a … is a nightmare.
I use
multiple record INSERTs (150 each time), … KEY for every capital letter
column, and a
different AUTO_INCREMENT …
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