fix: Precision loss on extremely large floating-point numbers

Sergey Tatarintsev · Sergey Tatarintsev · commit a438e61e2aba · 2023-11-06T15:26:42.000+01:00
Sets `extra_float_digits` setting to 1 when connecting to DB. For older (<12) Postgres, this should be enough to cover all values JS can store preciesely. For 12+ postgres this setting should have no effect. Fix brianc#3092
diff --git a/packages/pg-protocol/src/serializer.ts b/packages/pg-protocol/src/serializer.ts
@@ -26,6 +26,7 @@ const startup = (opts: Record<string, string>): Buffer => {
   }
 
   writer.addCString('client_encoding').addCString('UTF8')
+  writer.addCString('extra_float_digits').addCString('1')
 
   var bodyBuffer = writer.addCString('').flush()
   // this message is sent without a code
diff --git a/packages/pg/test/integration/client/type-coercion-tests.js b/packages/pg/test/integration/client/type-coercion-tests.js
@@ -108,7 +108,7 @@ var types = [
   },
   {
     name: 'double precision',
-    values: [-101.3, -1.2, 0, 1.2, 101.1, null],
+    values: [-101.3, -1.2, 0, 1.2, 101.1, Number.MAX_SAFE_INTEGER, null],
   },
   {
     name: 'timestamptz',

Original file line number	Diff line number	Diff line change
`@@ -26,6 +26,7 @@ const startup = (opts: Record<string, string>): Buffer => {`
`26`	`26`	`}`
`27`	`27`
`28`	`28`	`writer.addCString('client_encoding').addCString('UTF8')`
	`29`	`+ writer.addCString('extra_float_digits').addCString('1')`
`29`	`30`
`30`	`31`	`var bodyBuffer = writer.addCString('').flush()`
`31`	`32`	`// this message is sent without a code`
Original file line number	Diff line number	Diff line change
`@@ -108,7 +108,7 @@ var types = [`
`108`	`108`	`},`
`109`	`109`	`{`
`110`	`110`	`name: 'double precision',`
`111`		`- values: [-101.3, -1.2, 0, 1.2, 101.1, null],`
	`111`	`+ values: [-101.3, -1.2, 0, 1.2, 101.1, Number.MAX_SAFE_INTEGER, null],`
`112`	`112`	`},`
`113`	`113`	`{`
`114`	`114`	`name: 'timestamptz',`