82 lines
2.5 KiB
Plaintext
82 lines
2.5 KiB
Plaintext
[role="xpack"]
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[testenv="basic"]
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[[sql-index-patterns]]
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== Index patterns
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{es-sql} supports two types of patterns for matching multiple indices or tables:
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* {es} multi-index
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The {es} notation for enumerating, including or excluding <<multi-index,multi index syntax>>
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is supported _as long_ as it is quoted or escaped as a table identifier.
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For example:
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["source","sql",subs="attributes,callouts,macros"]
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----
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include-tagged::{sql-specs}/docs.csv-spec[showTablesEsMultiIndex]
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----
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Notice the pattern is surrounded by double quotes `"`. It enumerated `*` meaning all indices however
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it excludes (due to `-`) all indices that start with `l`.
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This notation is very convenient and powerful as it allows both inclusion and exclusion, depending on
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the target naming convention.
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The same kind of patterns can also be used to query multiple indices or tables.
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For example:
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["source","sql",subs="attributes,callouts,macros"]
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----
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include-tagged::{sql-specs}/docs.csv-spec[fromTablePatternQuoted]
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----
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NOTE: There is the restriction that all resolved concrete tables have the exact same mapping.
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* SQL `LIKE` notation
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The common `LIKE` statement (including escaping if needed) to match a wildcard pattern, based on one `_`
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or multiple `%` characters.
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Using `SHOW TABLES` command again:
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["source","sql",subs="attributes,callouts,macros"]
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----
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include-tagged::{sql-specs}/docs.csv-spec[showTablesLikeWildcard]
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----
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The pattern matches all tables that start with `emp`.
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This command supports _escaping_ as well, for example:
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["source","sql",subs="attributes,callouts,macros"]
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----
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include-tagged::{sql-specs}/docs.csv-spec[showTablesLikeEscape]
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----
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Notice how now `emp%` does not match any tables because `%`, which means match zero or more characters,
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has been escaped by `!` and thus becomes an regular char. And since there is no table named `emp%`,
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an empty table is returned.
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In a nutshell, the differences between the two type of patterns are:
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[cols="^h,^,^",options="header"]
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|===
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| Feature | Multi index | SQL `LIKE`
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| Type of quoting | `"` | `'`
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| Inclusion | Yes | Yes
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| Exclusion | Yes | No
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| Enumeration | Yes | No
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| One char pattern | No | `_`
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| Multi char pattern | `*` | `%`
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| Escaping | No | `ESCAPE`
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|===
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Which one to use, is up to you however try to stick to the same one across your queries for consistency.
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NOTE: As the query type of quoting between the two patterns is fairly similar (`"` vs `'`), {es-sql} _always_
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requires the keyword `LIKE` for SQL `LIKE` pattern.
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