58 lines
1.1 KiB
Markdown
58 lines
1.1 KiB
Markdown
+++
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date = "2009-08-20"
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title = "Once and for all: Rails migrations integer :limit option"
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tags = ["MySQL", "Ruby on Rails", "Rails", "sql", "migrations", "integer", "limit"]
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slug = "once-and-for-all-rails-migrations-integer-limit-option"
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I literally always have to look up the meaning of :limit in migrations when it comes to integer values. Here's an overview. Now let's memorise it (oh, this works for MySQL, other databases may work differently):
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<!--more-->
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<table>
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<tr>
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<th>:limit</th>
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<th>Numeric Type</th>
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<th>Column Size</th>
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<th>Max value</th>
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<tr>
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<tr>
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<td>1</td>
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<td>tinyint</td>
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<td>1 byte</td>
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<td>127</td>
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</tr>
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<tr>
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<td>2</td>
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<td>smallint</td>
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<td>2 bytes</td>
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<td>32767</td>
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</tr>
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<tr>
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<td>3</td>
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<td>mediumint</td>
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<td>3 byte</td>
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<td>8388607</td>
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</tr>
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<tr>
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<td>nil, 4, 11</td>
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<td>int(11)</td>
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<td>4 byte</td>
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<td>2147483647</td>
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</tr>
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<tr>
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<td>5..8</td>
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<td>bigint</td>
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<td>8 byte</td>
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<td>9223372036854775807</td>
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</tr>
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</table>
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<em>Note: by default MySQL uses signed integers and Rails has no way (that I know of) to change this behaviour. Subsequently, the max. values noted are for signed integers.</em>
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