10 lines
741 B
PHP
10 lines
741 B
PHP
Indexes are used to find rows with specific column values quickly.
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Without an index, the database must begin with the first row and then read through the entire table to find the relevant rows.
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<br \><br \>
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The larger the table, the more this consumes time. If the table has an index for the columns in question, the database
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can quickly determine the position to seek to in the middle of the data file without having to look at all the data.
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If a table has 1,000 rows, this is at least 100 times faster than reading rows one-by-one.
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<br \><br \>
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Indexes come with a cost as they slow down the inserts and updates. However, in general you
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should *<b>always</b>* use indexes for the fields that are used in sql where conditions.
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