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Support native UPSERTs & CrockroachDB #99

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Merged
JohnMcLear merged 3 commits into from
Mar 28, 2019
Merged

Support native UPSERTs & CrockroachDB #99

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ff629e4
centralized the UPSERT statement in a variable
muxator Aug 28, 2017
cc62236
when available, use native UPSERT
muxator Aug 28, 2017
ff3a45c
put the sql function creation statement into an inner scope
muxator Aug 28, 2017
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53 changes: 44 additions & 9 deletions postgres_db.js
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Original file line number Diff line number Diff line change
Expand Up @@ -39,7 +39,25 @@ exports.database.prototype.init = function(callback)
'"value" text NOT NULL, ' +
'CONSTRAINT store_pkey PRIMARY KEY (key))';

var createFunc = "CREATE OR REPLACE FUNCTION ueberdb_insert_or_update(character varying, text) " +
var _this = this;

// this variable will be given a value depending on the result of the
// feature detection
_this.upsertStatement = null;

/*
* - Detects if this Postgres version supports INSERT .. ON CONFLICT
* UPDATE (PostgreSQL >= 9.5 and CockroachDB)
* - If upsert is not supported natively, creates in the DB a pl/pgsql
* function that emulates it
* - Performs a side effect, setting _this.upsertStatement to the sql
* statement that needs to be used, based on the detection result
* - calls the callback
*/
function detectUpsertMethod(callback) {
var upsertViaFunction = "SELECT ueberdb_insert_or_update($1,$2)";
var upsertNatively = "INSERT INTO store(key, value) VALUES ($1, $2) ON CONFLICT (key) DO UPDATE SET value = excluded.value";
var createFunc = "CREATE OR REPLACE FUNCTION ueberdb_insert_or_update(character varying, text) " +
"RETURNS void AS $$ " +
"BEGIN " +
" IF EXISTS( SELECT * FROM store WHERE key = $1 ) THEN " +
Expand All @@ -50,16 +68,33 @@ exports.database.prototype.init = function(callback)
" RETURN; " +
"END; " +
"$$ LANGUAGE plpgsql;";

this.db.query(createFunc, []);

var _this = this;

var testNativeUpsert = "EXPLAIN " + upsertNatively;

_this.db.query(testNativeUpsert, ["test-key", "test-value"], function(err, results) {
if (err) {
// the UPSERT statement failed: we will have to emulate it via
// an sql function
_this.upsertStatement = upsertViaFunction;

// actually create the emulation function
_this.db.query(createFunc, [], callback);

return;
}

// if we get here, the EXPLAIN UPSERT succeeded, and we can use a
// native UPSERT
_this.upsertStatement = upsertNatively;
callback();
});
}

this.db.query(testTableExists, function(err, result) {
if (result.rows.length == 0) {
_this.db.query(createTable, callback);
_this.db.query(createTable, detectUpsertMethod(callback));
} else {
callback();
detectUpsertMethod(callback);
}
});
}
Expand Down Expand Up @@ -117,7 +152,7 @@ exports.database.prototype.set = function (key, value, callback)
}
else
{
this.db.query("SELECT ueberdb_insert_or_update($1,$2)", [key,value], callback);
this.db.query(_this.upsertStatement, [key,value], callback);
}
}

Expand Down Expand Up @@ -160,7 +195,7 @@ exports.database.prototype.doBulk = function (bulk, callback)
{
if (!replaceVALs.length < 1) {
for (var v in replaceVALs) {
_this.db.query("SELECT ueberdb_insert_or_update($1,$2)", replaceVALs[v], callback);
_this.db.query(_this.upsertStatement, replaceVALs[v], callback);
}
} else {
callback();
Expand Down