problem-list.md

The file will record many mistakes, errors, questions, problems i faced when making the practise

Problems

1. Mysql Error: The total number of locks exceeds the lock table size

• sql: DELETE FROM zhihu_answers WHERE id > 10000000;

2. Bad Performance: When executing count(*) operations on a mysql table which contains more than 10 million rows of data

• sql: SELECT count(*) FROM zhihu_accounts;
• optimize: SELECT max(id) FROM zhihu_accounts;

3. Bad Performance: When concurrent inserting much more data into database, later insertions will be very slow.

• sql: INSERT INTO TABLE zhihu_answers(...fields) VALUES(...fields)