Prepared Statement API #15
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Really nice work on this 👍
One nice addition to this could be a closure-based method that automatically frees the prepared query when done.
let res = db.prepare("SELECT ? as foo") { query in
let a = query.execute("a")
let b = query.execute("b")
let c = query.execute("c")
return .whenAllSucceed([a, b, c], on: db.eventLoop)
}
print(res) // ELFuture<[[PostgresRow]]>
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Hi @tanner0101, Yeah I still thinking about nicer ways to deal with the lifecycle of a prepared statement. However I am probably not getting back to this before early next week. |
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Any updates on this one? |
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@tanner0101 sorry I thought I pushed this a long time ago, I'll get this fixed up tonight. |
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Thanks for the updates! Sorry this one slipped through my feed. Just some minor nits then this is good to go 👍
| import Foundation | ||
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| extension PostgresDatabase { | ||
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| } | ||
| } | ||
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| public func prepare(query: String, handler: @escaping (PreparedQuery)->EventLoopFuture<[[PostgresRow]]>)->EventLoopFuture<[[PostgresRow]]> { |
Sources/PostgresNIO/Connection/PostgresDatabase+PreparedQuery.swift
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| let conn = try PostgresConnection.test(on: eventLoop).wait() | ||
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| defer { try! conn.close().wait() } | ||
| let prepared = try conn.prepare(query: "SELECT 1 as one;").wait() |
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Is this missing a deallocate for the prepared query? Maybe we should add an assertion to make sure it gets deallocated.
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A query doesn't need to get deallocated, because the session is closed by the end of this test.
Maybe deallocate is a bad name here because in most cases it refers to memory.
# Conflicts: # Sources/PostgresNIO/Connection/PostgresDatabase+PreparedQuery.swift # Tests/NIOPostgresTests/NIOPostgresTests.swift
# Conflicts: # Tests/NIOPostgresTests/NIOPostgresTests.swift
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| } | ||
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| public func deallocate() -> EventLoopFuture<Void> { | ||
| return database.query("DEALLOCATE \"\(name)\"").map { _ in } |
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I think this should be done using the special close message instead of a separate query. This can be added similar to other PostgresMessage+... types.
From: https://www.postgresql.org/docs/9.3/protocol-flow.html
The Close message closes an existing prepared statement or portal and releases resources. It is not an error to issue Close against a nonexistent statement or portal name. The response is normally CloseComplete, but could be ErrorResponse if some difficulty is encountered while releasing resources. Note that closing a prepared statement implicitly closes any open portals that were constructed from that statement.
From: https://www.postgresql.org/docs/9.3/protocol-message-formats.html
Close (F)
Byte1('C')
Identifies the message as a Close command.
Int32
Length of message contents in bytes, including self.
Byte1
'S' to close a prepared statement; or 'P' to close a portal.
String
The name of the prepared statement or portal to close (an empty string selects the unnamed prepared statement or portal).
CloseComplete (B)
Byte1('3')
Identifies the message as a Close-complete indicator.
Int32(4)
Length of message contents in bytes, including self.
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Yeah, good point, fixed in the last commit.
* update docs * update versions * add explicit check for binary for array encoding, #92 * Prepared Statement API (#15) * Added an API for prepared queries # Conflicts: # Sources/PostgresNIO/Connection/PostgresDatabase+PreparedQuery.swift # Tests/NIOPostgresTests/NIOPostgresTests.swift * Updated testPreparedQuery to close the connection # Conflicts: # Tests/NIOPostgresTests/NIOPostgresTests.swift * Added a DEALLOCATE api * Added a closure based API * Implemented log(to:) * Made prepared query a strcut * Spacing fixes * Implement 'Close' command for prepared statements * copy data row column slice (#96) * copy data row column slice * fix double read Co-authored-by: Thomas Bartelmess <tbartelmess@marketcircle.com>
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This is still a work in progress, there should be more code-sharing between the "normal" query and prepared queries.
It also still lacks an API to deallocate queries, and a more comprehensive test suite.