正在加载视频...

视频加载失败

加载此视频时出现问题。这可能是由于临时网络问题，或视频可能不可用。

Database table size impacts performance in more ways than one: a) B-tree depth. Using 8k pages and a 16b uuid: 1 level = ~370 rows 2 levels = ~138k rows 3 levels = ~50m rows 4 levels = ~20b rows The lookup cost on a table with 100k rows... is not the same as one with 1b rows. This can apply both to the table itself (MySQL cluster index) as well as the indexes. Sometimes a single query requires many of them. b) Small table → fits in RAM → fast reads. The larger the table, the more likely to read from disk plus churn the cache. c) # of indexes. Each adds maintenance overhead for insertions, and for Postgres vacuum overhead as well. Keep an eye on this! It's useful to take regular stock of your tables + indexes. Clean bloat. Remove unused indexes. Partition if needed.show more

Ben Dicken

35,680 subscribers

211,870 次观看 • 2 个月前 •via X (Twitter)

教育科学技术

Anya Rossi• Live Now

Private livecam show

0 条评论

暂无评论

原始帖子的评论将显示在这里

相关视频

SQL has levels to it: - level 1 SELECT, FROM, WHERE, GROUP BY, HAVING, LIMIT Master these basic keywords and you’ll be well on your way to mastering SQL. - level 2 Mastering JOINs: Most common JOINs: INNER and LEFT Less common JOINs: FULL OUTER Joins you should avoid almost always: RIGHT and CROSS JOIN Mastering common table expressions (CTEs). The WITH keyword defines a CTE which you can imagine as a “variable” that you can query later. Using variables like this you can master algorithm techniques like recursion, breadth first search and more! CTEs also make your SQL much more readable and make your coworkers hate you less compared to nested sub queries. - level 3 Mastering window functions Window functions have 3 pieces: The function (i.e. SUM, RANK, AVG) The over clause to start the window The window definition which has 3 pieces: - how to split the window up with PARTITION BY - how to order the window with ORDER BY - how to restrict the window size with ROWS clause (useful for rolling monthly averages) Understand RANK vs DENSE_RANK vs ROW_NUMBER, I have been asked this in interviews a million times. - level 4 You understand table scans, b-tree indexes, and partitioning schemes to increase performance. Doing something like COUNT(CASE WHEN) is much better than doing multiple queries with a UNION ALL. UNION ALL is terrible for all sorts of reasons that I don’t want to get into in this post. B-trees indexes allow for efficient scanning of data in the WHERE clause. Use explain plans to understand if an index is actually being used or not! Partitioning is similar to indexes except it’s a “poor mans” index. It just keeps data in specific folders and skips the folders that don’t include the data I question. What else did I miss for mastering SQL?

SQL has levels to it: - level 1 SELECT, FROM, WHERE, GROUP BY, HAVING, LIMIT Master these basic keywords and you’ll be well on your way to mastering SQL. - level 2 Mastering JOINs: Most common JOINs: INNER and LEFT Less common JOINs: FULL OUTER Joins you should avoid almost always: RIGHT and CROSS JOIN Mastering common table expressions (CTEs). The WITH keyword defines a CTE which you can imagine as a “variable” that you can query later. Using variables like this you can master algorithm techniques like recursion, breadth first search and more! CTEs also make your SQL much more readable and make your coworkers hate you less compared to nested sub queries. - level 3 Mastering window functions Window functions have 3 pieces: The function (i.e. SUM, RANK, AVG) The over clause to start the window The window definition which has 3 pieces: - how to split the window up with PARTITION BY - how to order the window with ORDER BY - how to restrict the window size with ROWS clause (useful for rolling monthly averages) Understand RANK vs DENSE_RANK vs ROW_NUMBER, I have been asked this in interviews a million times. - level 4 You understand table scans, b-tree indexes, and partitioning schemes to increase performance. Doing something like COUNT(CASE WHEN) is much better than doing multiple queries with a UNION ALL. UNION ALL is terrible for all sorts of reasons that I don’t want to get into in this post. B-trees indexes allow for efficient scanning of data in the WHERE clause. Use explain plans to understand if an index is actually being used or not! Partitioning is similar to indexes except it’s a “poor mans” index. It just keeps data in specific folders and skips the folders that don’t include the data I question. What else did I miss for mastering SQL?

Zach Wilson

33,426 次观看 • 1 个月前

SQL has levels to it: - level 1 SELECT, FROM, WHERE, GROUP BY, HAVING, LIMIT Master these basic keywords and you’ll be well on your way to mastering SQL. - level 2 Mastering JOINs: Most common JOINs: INNER and LEFT Less common JOINs: FULL OUTER Joins you should avoid almost always: RIGHT and CROSS JOIN Mastering common table expressions (CTEs). The WITH keyword defines a CTE which you can imagine as a “variable” that you can query later. Using variables like this you can master algorithm techniques like recursion, breadth first search and more! CTEs also make your SQL much more readable and make your coworkers hate you less compared to nested sub queries. - level 3 Mastering window functions Window functions have 3 pieces: The function (i.e. SUM, RANK, AVG) The over clause to start the window The window definition which has 3 pieces: - how to split the window up with PARTITION BY - how to order the window with ORDER BY - how to restrict the window size with ROWS clause (useful for rolling monthly averages) Understand RANK vs DENSE_RANK vs ROW_NUMBER, I have been asked this in interviews a million times. - level 4 You understand table scans, b-tree indexes, and partitioning schemes to increase performance. Doing something like COUNT(CASE WHEN) is much better than doing multiple queries with a UNION ALL. UNION ALL is terrible for all sorts of reasons that I don’t want to get into in this post. B-trees indexes allow for efficient scanning of data in the WHERE clause. Use explain plans to understand if an index is actually being used or not! Partitioning is similar to indexes except it’s a “poor mans” index. It just keeps data in specific folders and skips the folders that don’t include the data I question. What else did I miss for mastering SQL?

SQL has levels to it: - level 1 SELECT, FROM, WHERE, GROUP BY, HAVING, LIMIT Master these basic keywords and you’ll be well on your way to mastering SQL. - level 2 Mastering JOINs: Most common JOINs: INNER and LEFT Less common JOINs: FULL OUTER Joins you should avoid almost always: RIGHT and CROSS JOIN Mastering common table expressions (CTEs). The WITH keyword defines a CTE which you can imagine as a “variable” that you can query later. Using variables like this you can master algorithm techniques like recursion, breadth first search and more! CTEs also make your SQL much more readable and make your coworkers hate you less compared to nested sub queries. - level 3 Mastering window functions Window functions have 3 pieces: The function (i.e. SUM, RANK, AVG) The over clause to start the window The window definition which has 3 pieces: - how to split the window up with PARTITION BY - how to order the window with ORDER BY - how to restrict the window size with ROWS clause (useful for rolling monthly averages) Understand RANK vs DENSE_RANK vs ROW_NUMBER, I have been asked this in interviews a million times. - level 4 You understand table scans, b-tree indexes, and partitioning schemes to increase performance. Doing something like COUNT(CASE WHEN) is much better than doing multiple queries with a UNION ALL. UNION ALL is terrible for all sorts of reasons that I don’t want to get into in this post. B-trees indexes allow for efficient scanning of data in the WHERE clause. Use explain plans to understand if an index is actually being used or not! Partitioning is similar to indexes except it’s a “poor mans” index. It just keeps data in specific folders and skips the folders that don’t include the data I question. What else did I miss for mastering SQL?

Zach Wilson

79,472 次观看 • 1 年前

Played around with using a Vulkan Strap on seated cable rows this morning….have to say, I can truly feel the back using the strap as it locks in the elbows.

Played around with using a Vulkan Strap on seated cable rows this morning….have to say, I can truly feel the back using the strap as it locks in the elbows.

💯 WS 💯 🇺🇸

21,304 次观看 • 2 个月前

So bizarre to see the people in the first few rows dead center at a Phish NYE concert at start of Gamehendge... Have more room than anyone else in the entire arena. WTF even is this? I saw the same thing in Mexico. People up close with more space than those 30 rows back.

So bizarre to see the people in the first few rows dead center at a Phish NYE concert at start of Gamehendge... Have more room than anyone else in the entire arena. WTF even is this? I saw the same thing in Mexico. People up close with more space than those 30 rows back.

Andrew Duddy

81,935 次观看 • 2 年前

This is one of the BEST Back exercises known to man It’s probably Top 3 if we’re being honest “Better than Chest Supported Dumbbell Rows???” Yes…similar to but BETTER THAN Chest Supported Dumbbell Rows The small setup hassle is WELL worth it Everyone that tries it LOVES IT

This is one of the BEST Back exercises known to man It’s probably Top 3 if we’re being honest “Better than Chest Supported Dumbbell Rows???” Yes…similar to but BETTER THAN Chest Supported Dumbbell Rows The small setup hassle is WELL worth it Everyone that tries it LOVES IT

Dean Turner

57,500 次观看 • 1 个月前

LAFD Bureau Of Supply and Maintenance: Went to the LAFD repair yard to document how many trucks are waiting to be repaired. Rows and rows of equipment. We could use this stuff right now.

LAFD Bureau Of Supply and Maintenance: Went to the LAFD repair yard to document how many trucks are waiting to be repaired. Rows and rows of equipment. We could use this stuff right now.

Film The Police LA

258,310 次观看 • 1 年前

The home gym alternative to Chest Supported T Bar Rows is Chest Supported Dumbbell Rows And here is an EXCELLENT example of how to setup for and execute them PROPERLY from Jeff Alberts

The home gym alternative to Chest Supported T Bar Rows is Chest Supported Dumbbell Rows And here is an EXCELLENT example of how to setup for and execute them PROPERLY from Jeff Alberts

Dean Turner

156,167 次观看 • 1 个月前

Rows are one of my favorite finishers. You can go heavy to get a great ego boost to really make the rest of your day as positive as it can be.

Rows are one of my favorite finishers. You can go heavy to get a great ego boost to really make the rest of your day as positive as it can be.

Austin Tejas

13,373 次观看 • 16 天前

most people stick to just 1 or 2 tables they are familiar with when writing their SQL queries in we built the ability to search for tables, preview tables and easily sample rows from a table so you can find the ones you need + even discover new tables data discovery is a big problem even in small companies. most data doesn't get analyzed because most of company doesn't know it exists

most people stick to just 1 or 2 tables they are familiar with when writing their SQL queries in we built the ability to search for tables, preview tables and easily sample rows from a table so you can find the ones you need + even discover new tables data discovery is a big problem even in small companies. most data doesn't get analyzed because most of company doesn't know it exists

rahul

11,550 次观看 • 10 个月前

To look around the stadium during “Badlands” and to see the same scene in the last rows of the upper deck as it was in the pit was truly amazing.

To look around the stadium during “Badlands” and to see the same scene in the last rows of the upper deck as it was in the pit was truly amazing.

That One Lyric Podcast

46,851 次观看 • 20 天前

Inverted Rows an underappreciated tool in the pull family. Its more than a gateway drug to performing chin ups and marries up well with horizontal pushes. We try to teach and cue it as same path as a Bench Press. Here are some different versions of the Inverted Row. #strengthandconditioning #strengthandconditioningcoach #workout #backworkout #invertedrow #athlete #coach

Inverted Rows an underappreciated tool in the pull family. Its more than a gateway drug to performing chin ups and marries up well with horizontal pushes. We try to teach and cue it as same path as a Bench Press. Here are some different versions of the Inverted Row. #strengthandconditioning #strengthandconditioningcoach #workout #backworkout #invertedrow #athlete #coach

James Burk

38,436 次观看 • 3 个月前

today's experiment: silky smooth fixed-height virtual table, rendered with canvas tested with 10^50+ rows of dynamic data

today's experiment: silky smooth fixed-height virtual table, rendered with canvas tested with 10^50+ rows of dynamic data

f1shy-dev

93,442 次观看 • 9 个月前

This reminds me of all the people that choose Barbell Rows over Chest Supported T Bar Rows tbh Same energy

This reminds me of all the people that choose Barbell Rows over Chest Supported T Bar Rows tbh Same energy

Dean Turner

16,101 次观看 • 11 个月前

JUST IN: Tens of thousands of acres in the Amazon rainforest have been cut down to build a road for the COP30 climate summit in Brazil. Huge swaths of land are getting cleared out to "ease traffic to the city" of Belem for a new highway. Video shows rows and rows of deforested land.

JUST IN: Tens of thousands of acres in the Amazon rainforest have been cut down to build a road for the COP30 climate summit in Brazil. Huge swaths of land are getting cleared out to "ease traffic to the city" of Belem for a new highway. Video shows rows and rows of deforested land.

Eric Daugherty

220,629 次观看 • 1 年前

MySQL vs Postgres: storage engine addition. Clustered indexes (MySQL) and heap tables (Postgres) each have unique advantages. Covered the differences and practical implications in the latest stream.

MySQL vs Postgres: storage engine addition. Clustered indexes (MySQL) and heap tables (Postgres) each have unique advantages. Covered the differences and practical implications in the latest stream.

Ben Dicken

19,991 次观看 • 28 天前

🚨BREAKING: British veteran breaks down live on TV over state of the country: "Rows and rows of white tombs for what? A country of today? No, I'm sorry. The sacrifice wasn't worth the result. I fought for freedom, and it's darn-sight worse now than when I fought."

🚨BREAKING: British veteran breaks down live on TV over state of the country: "Rows and rows of white tombs for what? A country of today? No, I'm sorry. The sacrifice wasn't worth the result. I fought for freedom, and it's darn-sight worse now than when I fought."

Inevitable West

11,253,061 次观看 • 7 个月前

The Executive is defined by inaction, so is happy with the distraction of daily rows on signs or statues. If we want to give young people a reason not to get on a plane to Australia, we need to offer more them more than one never-ending Old Firm game.

The Executive is defined by inaction, so is happy with the distraction of daily rows on signs or statues. If we want to give young people a reason not to get on a plane to Australia, we need to offer more them more than one never-ending Old Firm game.

Matthew O'Toole

10,657 次观看 • 1 年前

Using one child as a table to eat off of while the other is in the back screaming for food. Mother of the year 🥇

Sensitive content

Using one child as a table to eat off of while the other is in the back screaming for food. Mother of the year 🥇

Liberacrat™️

174,813 次观看 • 6 个月前

This week's pose and cable rows example with 185 on the stack

This week's pose and cable rows example with 185 on the stack

Sam_hears_all

19,878 次观看 • 1 年前