One recommendation for the benchmark - choose the date randomly, ie have your start/start+1 be a random value in the range of values (min, max). The reason you want to do that is because doing a repeated benchmark on the same date, you are very likely hitting either cpu cache or other caching in the application tier, doing each one of the queries in the iteration loop with a random date is both more realistic in terms of actual user behavior as well as avoids the cache hit scenario.
Yeah this is what I got in mind..also adding the number of repeated tests for the "faster method" while reducing the repeats for the "slow" method accentuates this issue --> makes the slow method slower and the fast method faster --> widening the gap. For better result, benchmarks should be done using the same repeat times.
Covering index is great but one must keep in mind adding only necessary columns to the composite index, otherwise the DB size will get bigger unnecessarily. But again, why the reversed index (email, created_at) was created for? I didn't get it🤔 Thanks Aaron!
Not only will the size grow but insertion/updates will increase in time as well, as the indexes will need to be updated as well. The more you index, and the more indexes you have, the longer the writes will be.
Would love a video on when to use bitmap indexes on low cardinality columns with dynamic multi-column searching (e.g. slicing and dicing data in a dashboard). I know it’s faster than b-tree indexes, but a video showing it would be awesome.
dude your videos are the best. I've learned so much from you. Specifically: your videos cover ONE topic very well, very clearly, and very thoroughly (is that a word)? Thanks for your work!! You're a great speaker/teacher as well.
This benchmark might be very worng due to caching. Idk how mysql works but every db i worked with has few layers of caching and repeating one query over and over might benchmark only cache itself.
get() method is different to select() cuz get() is for collection or object while select() is for db query. I think it's better to use select() instead of get()
Hey Aaron, one thing I was curious about that might be right up your alley: What indexes should I use for a table that can be filtered on any column? Usually you would index fields commonly found in your where statement, but you can't just index every column right?
Alright so how we can apply this technique to the searching or filtering stuff ? I mean in a real application , is it mean we have to create different type of index?
No, it totally based on your application needs. like for example from application requirements Search: i would use algolia. Reports: create Views or SP. Quey On Large single table: index or combin index. Quey on Join table with ORM: will use Ladacache Package for cache in redis
Your videos are great. I love them. I have a suggestion for you. Could you make a video explaining how to optimize this type of query: select * from order as o join order_item as oi on oi.order_id = o.id where o.client_id = 123 and oi.product_id = 321; Even if we have an index on the column order.client_id and another one on the column order_item.product_id, this query could be slow if the filtered client_id and product_id appear in many rows. That's because the join implies a lot of index lookups on the other table. The only way I know to optimize this type of query is to create a materialized view with data from both tables and create a single index on both columns. This way, the database can filter both columns at the same time and won't have to perform separate index lookups. The problem is that MySQL doesn't have materialized views, as far as I know.
Really useful video, especially the information about the primary key within the compound index. Does that mean it is useless to create compound indexes containing the primary key (for example created_at+id) ?
you should mentioned that PK is included in index only on SOME mysql/mariadb engines (i.e. innodb, maybe others); for myisam (well, who use myisam anymore?) and mostly other engines the PK is not included in the indexes in rest, great video (as usual), maybe developers should learn more about how a database work in order to not produce junk queries; but with ORMs nowadays, you mostly don't have control anymore about what is executed ...
Interesting that you mentioned PostgreSQL here and its ability to bring along extra columns with index. Even though it can do that, i was able to make my query faster after using indexes using the method you showed. It went from 450ms avg (single index) to 240ms avg (multiple indexes with ride along columns)
In my big table, I noticed a better performance if I'm using the entire datetime for created_at, like: Where created_at >= '2023-12-03 00:00:00' and created_at
Hey Aaron, great video but I think you missed something here. I would tell everyone to not add index that they don’t need in their app. Multiple reasons why this is unadvisable but in the end it just ends up slowing the query back down. So in a table with 5Mil entries and 10-20 columns, you would not create a composite key ok created at and any other combination of column/columns you might need. Related to this, you can make a video showing people that mysql only uses only an index when performing searches and that it calculates automatically which index is best to use. ( and us such, calculating that for 20 indexes on a table will result in slowing stuff down )
![Coheed and Cambria - Searching for Tomorrow [Official Video]](http://i.ytimg.com/vi/hDsYGLbmadg/mqdefault.jpg)
One recommendation for the benchmark - choose the date randomly, ie have your start/start+1 be a random value in the range of values (min, max). The reason you want to do that is because doing a repeated benchmark on the same date, you are very likely hitting either cpu cache or other caching in the application tier, doing each one of the queries in the iteration loop with a random date is both more realistic in terms of actual user behavior as well as avoids the cache hit scenario.
Yeah this is what I got in mind..also adding the number of repeated tests for the "faster method" while reducing the repeats for the "slow" method accentuates this issue --> makes the slow method slower and the fast method faster --> widening the gap.
For better result, benchmarks should be done using the same repeat times.
There's something satisfying in optimizing code, databases, etc. When you gain significant performance, it just feels right :)
Covering index is great but one must keep in mind adding only necessary columns to the composite index, otherwise the DB size will get bigger unnecessarily.
But again, why the reversed index (email, created_at) was created for? I didn't get it🤔
Thanks Aaron!
Not only will the size grow but insertion/updates will increase in time as well, as the indexes will need to be updated as well. The more you index, and the more indexes you have, the longer the writes will be.
@@master74200 Exactly👍
This is awesome! I'd love to see a video at some point talking about best practices for modeling time series data in MySQL
Would love a video on when to use bitmap indexes on low cardinality columns with dynamic multi-column searching (e.g. slicing and dicing data in a dashboard). I know it’s faster than b-tree indexes, but a video showing it would be awesome.
dude your videos are the best. I've learned so much from you. Specifically: your videos cover ONE topic very well, very clearly, and very thoroughly (is that a word)? Thanks for your work!! You're a great speaker/teacher as well.
This benchmark might be very worng due to caching. Idk how mysql works but every db i worked with has few layers of caching and repeating one query over and over might benchmark only cache itself.
Wow, genius!! That benchmark tool is very useful too
Man, I dont usually write comments, but your videos are on the next level. They are just perfect. Amazing work! Great Job!
That's a lot of 7s...
I got caught in a loop there
@@PlanetScale Loved it. When recursion goes wrong.
A joke only for the dedicated few
get() method is different to select() cuz get() is for collection or object while select() is for db query. I think it's better to use select() instead of get()
Hey Aaron, one thing I was curious about that might be right up your alley: What indexes should I use for a table that can be filtered on any column? Usually you would index fields commonly found in your where statement, but you can't just index every column right?
Alright so how we can apply this technique to the searching or filtering stuff ? I mean in a real application , is it mean we have to create different type of index?
No, it totally based on your application needs. like for example from application requirements
Search: i would use algolia.
Reports: create Views or SP.
Quey On Large single table: index or combin index.
Quey on Join table with ORM: will use Ladacache Package for cache in redis
Your videos are great. I love them.
I have a suggestion for you. Could you make a video explaining how to optimize this type of query:
select *
from order as o
join order_item as oi on oi.order_id = o.id
where o.client_id = 123
and oi.product_id = 321;
Even if we have an index on the column order.client_id and another one on the column order_item.product_id, this query could be slow if the filtered client_id and product_id appear in many rows. That's because the join implies a lot of index lookups on the other table. The only way I know to optimize this type of query is to create a materialized view with data from both tables and create a single index on both columns. This way, the database can filter both columns at the same time and won't have to perform separate index lookups. The problem is that MySQL doesn't have materialized views, as far as I know.
But MySQL does have views. You can use that
Really useful video, especially the information about the primary key within the compound index. Does that mean it is useless to create compound indexes containing the primary key (for example created_at+id) ?
you should mentioned that PK is included in index only on SOME mysql/mariadb engines (i.e. innodb, maybe others); for myisam (well, who use myisam anymore?) and mostly other engines the PK is not included in the indexes
in rest, great video (as usual), maybe developers should learn more about how a database work in order to not produce junk queries; but with ORMs nowadays, you mostly don't have control anymore about what is executed ...
Interesting that you mentioned PostgreSQL here and its ability to bring along extra columns with index. Even though it can do that, i was able to make my query faster after using indexes using the method you showed. It went from 450ms avg (single index) to 240ms avg (multiple indexes with ride along columns)
is created_at stored as string?
can you provide the data for the queries that you are using
I wonder what would happen if we even add partition for year?
Me too. My queries only deal with a few hundred rows so it doesn't matter for me lol, but it would be interesting to see.
In my big table, I noticed a better performance if I'm using the entire datetime for created_at, like:
Where created_at >= '2023-12-03 00:00:00'
and created_at
Hey Aaron, great video but I think you missed something here. I would tell everyone to not add index that they don’t need in their app. Multiple reasons why this is unadvisable but in the end it just ends up slowing the query back down. So in a table with 5Mil entries and 10-20 columns, you would not create a composite key ok created at and any other combination of column/columns you might need.
Related to this, you can make a video showing people that mysql only uses only an index when performing searches and that it calculates automatically which index is best to use. ( and us such, calculating that for 20 indexes on a table will result in slowing stuff down )
This is good stuff. Thank you.
A question : in mysql how to optimize count(*) on a table with more than 150m rows (I mean a large table) and surely I use where in it ?
Is there a way to test repeatedly without having MySQL buffering give better results for subsequent queries? Change InnoDB settings?
If you make your dataset much larger than available RAM then RDBMS would not be able to fully cache the data.
As always, AWESOME!
Aha! I knew you knew some things about Postgres!
I'm sure I've just missed it, but I'm not understanding why we had to create the inverse of that index
I think he skipped over that...
He created it to show with EXPLAIN that the planner chooses the other index. So the reverse isn't necessary
Paginators. Please help with optimizing pagination which usually implements a count(*)
dont do it :)
@@nunosdonato please elaborate
amazing, loved this content ...
If you ain't seeded, stay seated and watch this video!
You should release your editor theme settings... The Aron Theme... Make it happen. 💙
Video request 🙋🏻♂️have been hoping out for a while as it was mentioned on a previous video: geospatial indexes
PHP? I didn’t know you drove a Lamborghini
The fastest way is to remove the card in the hobby plan
13:05 : holly
Hello, thank you for your videos. I am improving my queries
Those damn sevens!!! :)) haha , top notch info, thank you. I did not considered about these type of situations, I'm smarter than yesterday now. ✌
Amazing
that terminal font is beautiful. care to put it on the description for less people asking?
this is the fastest query for mysql to process:
it takes 0.000000s and costs $0.00 to run.
EXPLAIN your queries please. And show us your schema!
8:43 thank you! I spoke too soon maybe.
Ha, I appreciate the enthusiasm