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(**
This module store the hash of the indexes ([extern_key]) for each table in
order to update the file if the configuration changed.
The hashes are stored in a table named [hashes] and are evaluated just
before inserting the values.
*)
open StdLabels
module Table = ImportDataTypes.Table
let ( let* ) = Result.bind
let create_table : 'a T.t -> unit T.result =
fun db ->
Sqlite3.exec db
"CREATE TABLE IF NOT EXISTS 'hashes' ('table' TEXT, 'hash' INTEGER, \
PRIMARY KEY ('table'))"
|> T.to_result
let evaluate : ImportAnalyser.Dependency.t -> int =
fun table ->
(* Extract all the references to this table *)
let keys =
List.map (ImportAnalyser.Dependency.keys table)
~f:(fun ImportAnalyser.Dependency.{ name; columns; expression } ->
ignore columns;
(name, expression))
in
Hashtbl.hash keys
let insert : 'a T.t -> ImportAnalyser.Dependency.t -> unit T.result =
fun db table ->
let source = ImportAnalyser.Dependency.table table in
let table_name = Table.name source in
let hash = evaluate table in
let query =
String.concat ~sep:""
[
"INSERT INTO 'hashes' ('table', 'hash') VALUES ('";
table_name;
"', :hash) ON CONFLICT(hashes.'table') DO UPDATE SET 'hash' = :hash";
]
in
let* statement =
try Ok (Sqlite3.prepare db query) with
| e -> Error e
in
let* _ = T.begin_transaction db in
let sql_data = Sqlite3.Data.INT (Int64.of_int hash) in
let* _ = Sqlite3.bind_name statement ":hash" sql_data |> T.to_result in
let* _ = T.to_result (Sqlite3.step statement) in
T.commit db
let query : 'a T.t -> ImportDataTypes.Table.t -> int option T.result =
fun db table ->
let table_name = Table.name table in
let query =
String.concat ~sep:""
[ "SELECT hash FROM 'hashes' WHERE hashes.'table' = '"; table_name; "'" ]
in
let* stmt =
try Ok (Sqlite3.prepare db query) with
| e -> Error e
in
let state, res =
Sqlite3.fold stmt ~init:None ~f:(fun _ d ->
Some (T.to_datatype (Array.get d 0)))
in
let* _ = T.to_result state in
match res with
| Some (ImportCSV.DataType.Integer i) -> Ok (Some i)
| _ -> Ok None
|
