MySQL timestamp index:Indexing on date timestamp
Indexing on date timestamp
2023年7月27日—IhaveaMySQLquerywhichrelyoncreated_atcolumninphp.Likethisselect*fromxyzwherecreated_atendOfMonth().。其他文章還包含有:「10.3.14IndexedLookupsfromTIMESTAMPColumns」、「Creatinganindexonatimestamptooptimizequery」、「mysql」、「mysql」、「MySQLindexondatetimecolumn」、「TimestampfiltersonindexesfieldsinMySQL」、「UnderstandingIndexcreationinMySQL」、「UnixtimestampField&Indexes」
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The optimizer performs an index scan, first converting the search value from the session time zone to UTC, then comparing the result to the UTC index entries.
Creating an index on a timestamp to optimize query
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Indexes in general are a good idea for regularly queried fields. The only downside to defining indexes is that they use extra storage space.
mysql
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This new version of your query modifies NOW() by 20 hours, and so can use an index to find exactly where the records start that have that timestamp.
mysql
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created_at is timestamp with index. But when I use EXPLAIN, the column filtered shows 10, which is bad. What could be the cause of this 10 ?
MySQL index on datetime column
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Indexing a datetime column in a large, frequently updated table can be a challenging decision. While indexing can improve query performance, it ...
Timestamp filters on indexes fields in MySQL
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Hello. I have a “order” table with “Time” field, containing a unix timestamp (seconds resolution) of each order. This field is indexed.
Understanding Index creation in MySQL
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When you create an index on a TIMESTAMP field or any other data type, MySQL doesn't store a hash of the value or the literal value itself as the index key.
Unix timestamp Field & Indexes
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When I index on the timestamp field, l_date_time(int(16)), the cardinality is the maximum (because there are no 2 times the same).