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110 lines
3.1 KiB
Markdown
110 lines
3.1 KiB
Markdown
# SQL query mapping
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The table.sql\_query module implements table interface using SQL queries.
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Definition:
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```
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table.sql_query {
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driver <driver name>
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dsn <data source name>
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lookup <lookup query>
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# Optional:
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init <init query list>
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list <list query>
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add <add query>
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del <del query>
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set <set query>
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}
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```
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Usage example:
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```
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# Resolve SMTP address aliases using PostgreSQL DB.
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modify {
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replace_rcpt sql_query {
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driver postgres
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dsn "dbname=maddy user=maddy"
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lookup "SELECT alias FROM aliases WHERE address = $1"
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}
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}
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```
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## Configuration directives
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***Syntax***: driver _driver name_ <br>
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***REQUIRED***
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Driver to use to access the database.
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Supported drivers: postgres, sqlite3 (if compiled with C support)
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***Syntax***: dsn _data source name_ <br>
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***REQUIRED***
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Data Source Name to pass to the driver. For SQLite3 this is just a path to DB
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file. For Postgres, see
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[https://pkg.go.dev/github.com/lib/pq?tab=doc#hdr-Connection\_String\_Parameters](https://pkg.go.dev/github.com/lib/pq?tab=doc#hdr-Connection\_String\_Parameters)
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***Syntax***: lookup _query_ <br>
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***REQUIRED***
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SQL query to use to obtain the lookup result.
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It will get one named argument containing the lookup key. Use :key
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placeholder to access it in SQL. The result row set should contain one row, one
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column with the string that will be used as a lookup result. If there are more
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rows, they will be ignored. If there are more columns, lookup will fail. If
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there are no rows, lookup returns "no results". If there are any error - lookup
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will fail.
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***Syntax***: init _queries..._ <br>
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***Default***: empty
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List of queries to execute on initialization. Can be used to configure RDBMS.
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Example, to improve SQLite3 performance:
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```
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table.sql_query {
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driver sqlite3
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dsn whatever.db
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init "PRAGMA journal_mode=WAL" \
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"PRAGMA synchronous=NORMAL"
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lookup "SELECT alias FROM aliases WHERE address = $1"
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}
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```
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**Syntax:** named\_args _boolean_ <br>
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**Default:** yes
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Whether to use named parameters binding when executing SQL queries
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or not.
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Note that maddy's PostgreSQL driver does not support named parameters and
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SQLite3 driver has issues handling numbered parameters:
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[https://github.com/mattn/go-sqlite3/issues/472](https://github.com/mattn/go-sqlite3/issues/472)
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***Syntax:*** add _query_ <br>
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***Syntax:*** list _query_ <br>
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***Syntax:*** set _query_ <br>
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***Syntax:*** del _query_ <br>
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***Default:*** none
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If queries are set to implement corresponding table operations - table becomes
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"mutable" and can be used in contexts that require writable key-value store.
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'add' query gets :key, :value named arguments - key and value strings to store.
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They should be added to the store. The query **should** not add multiple values
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for the same key and **should** fail if the key already exists.
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'list' query gets no arguments and should return a column with all keys in
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the store.
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'set' query gets :key, :value named arguments - key and value and should replace the existing
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entry in the database.
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'del' query gets :key argument - key and should remove it from the database.
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If named\_args is set to "no" - key is passed as the first numbered parameter
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($1), value is passed as the second numbered parameter ($2).
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