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33 lines
1.1 KiB
Markdown
33 lines
1.1 KiB
Markdown
# Integers In Postgres
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Postgres has three kinds of integers. Or rather three sizes of integers.
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There are `smallint` (`int2`), `integer` (`int4`), and `bigint` (`int8`)
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integers. As you might expect, they are 2 byte, 4 byte, and 8 byte integers
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respectively. They are also signed integers. All of this has implications
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for what ranges of integers can be represented by each type.
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The `smallint` integers have 2 bytes to use, so they can be used to
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represent integers from -32768 to +32767.
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The `integer` integers have 4 bytes to use, so they can be used to represent
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integers from -2147483648 to +2147483647.
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The `bigint` integers have 8 bytes to use, so they can be used to represent
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integers from -9223372036854775808 to +9223372036854775807.
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Though columns can be restricted to use a particular-sized integer, postgres
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is smart enough to default to `integer` and only use `bigint` as necessary
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when working with integers on the fly.
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```sql
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> select pg_typeof(55);
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pg_typeof
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-----------
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integer
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> select pg_typeof(99999999999999999);
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pg_typeof
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-----------
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bigint
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```
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