16,622 reputation
32960
bio website in.another.dimension
location Athens, Greece
age 46
visits member for 3 years, 5 months
seen 7 mins ago

Interests: math, programming and games, not necessarily in that order.


4m
comment sqlcmd returning NUL instead of NULL for tinyint column
Right but only this column is tinyint, which can hold values from 0 up to 255. i.e. numbers with up to 3 digits only.
1h
comment Index on 'GROUP BY' with functions
Yes, that's fine.
2h
comment Best Practice for database design (storing images to a database)
See the answers in the link that Matt provided. There are pros and cons for both ways (storing blobs vs. storing path to external files.)
2h
comment Index on 'GROUP BY' with functions
You changed the query from DATE(timestamp) to HOUR(timestamp). In your comments you mention users as well, yet the code has nothing about users. If you want good answers, please edit the question with the queries you have and the table definition. And you really should have done that in the first place, not after 3 days and having 4 people wasting their time answering a question that changes scope.
20h
reviewed Close How to fix the SQL from SQL Server to Oracle?
20h
reviewed Close DBMS database management system
2d
awarded  query-performance
2d
comment sqlcmd returning NUL instead of NULL for tinyint column
There is a (max_column_width = 3) setting or similar hidden somewhere that cuts the output that is longer than 3 chars?
2d
reviewed Reject suggested edit on View with left joins are very slow
2d
reviewed Close Automatically Transfer Files From server to Database
2d
reviewed Close Whether Logfile Shrinking is good or bad one for Performance in SQL?
2d
reviewed Approve suggested edit on View with left joins are very slow
Jul
25
revised Improving `GROUP BY` query performance in sqlite3
added 530 characters in body
Jul
25
comment Improving `GROUP BY` query performance in sqlite3
@FakeName Will you need the last ORDER BY ORDER BY di.max_retreivalTime;? I can add a version with the PK.
Jul
25
comment Improving `GROUP BY` query performance in sqlite3
It could be just a few as hundreds or thousands of rows. Big enough for the optimizer to consider using 2 indexes (or the clustered index and another non-clustered one) to fetch the data.
Jul
25
comment Improving `GROUP BY` query performance in sqlite3
I see, the unreal results I was talking about usually come with big tables and/or some several indexes existing. And not really sure about SQLite really - I've seen it in MySQL.
Jul
25
answered Improving `GROUP BY` query performance in sqlite3
Jul
25
comment Improving `GROUP BY` query performance in sqlite3
It usually seems to work fine in MySQL, too. Until it doesn't. It's not consistent behaviour.
Jul
25
comment Improving `GROUP BY` query performance in sqlite3
And if you do want (just 1 row per seriesName), why have ORDER BY and OFFSET? Just use LIMIT 200.
Jul
25
comment Improving `GROUP BY` query performance in sqlite3
The problem is far more worse. You can have rows in the result that include values from different rows (so rows that do not actually exist in the table! At least in MySQL's implementation, not sure about SQLite.)