Add a pg oracle

- define `datetime`, `printf` fns in pg so it produces similar
  output as sqlite

- tidy up input data to be less wide

To do: some fns to make it easy to generate a new test case. Probably
want to mount all the 3 parquets simultaneously and refer to the
sqlite table by the same name as the pg table.

parquet-generator/create-pg-db

@@ -0,0 +1,55 @@
+#!/bin/bash
+
+set -euo pipefail
+
+export PGUSER=postgres
+
+dropdb parquet || true
+createdb parquet
+
+here=$(readlink -f "$(dirname "${BASH_SOURCE[0]}")")
+
+psql parquet << EOF
+CREATE TABLE no_nulls(
+  rowid INT2,
+  bool_0 INT2,
+  int8_1 INT2,
+  int16_2 INT2,
+  int32_3 INT4,
+  int64_4 INT8,
+  ts_5 int8,
+  double_6 DOUBLE PRECISION,
+  string_7 TEXT,
+  string_8 TEXT,
+  binary_9 TEXT,
+  binary_10 TEXT
+);
+
+CREATE TABLE nulls (LIKE no_nulls);
+
+COPY no_nulls FROM '$here/no-nulls.csv';
+COPY nulls FROM '$here/nulls.csv';
+
+CREATE OR REPLACE FUNCTION quote(TEXT) RETURNS TEXT AS \$\$
+  BEGIN
+    RETURN \$1;
+  END;
+\$\$ LANGUAGE 'plpgsql' IMMUTABLE;
+
+CREATE OR REPLACE FUNCTION datetime(INT8, TEXT) RETURNS TEXT AS \$\$
+  BEGIN
+    RETURN to_timestamp(\$1) AT TIME ZONE 'UTC';
+  END;
+\$\$ LANGUAGE 'plpgsql' IMMUTABLE;
+
+CREATE OR REPLACE FUNCTION printf(TEXT, DOUBLE PRECISION) RETURNS TEXT AS \$\$
+  BEGIN
+    RETURN CAST(\$2 AS DECIMAL(10, 4))::TEXT;
+  END;
+\$\$ LANGUAGE 'plpgsql' IMMUTABLE;
+
+
+
+--COPY (SELECT rowid, bool_0, int8_1, int16_2, int32_3, int64_4, datetime(ts_5 / 1000, 'unixepoch'), double_6, string_7, string_8, quote(binary_9), quote(binary_10) FROM nulls LIMIT 3) TO STDOUT WITH (DELIMITER '|', NULL '');
+COPY (SELECT rowid, bool_0, int8_1, int16_2, int32_3, int64_4, datetime(ts_5 / 1000, 'unixepoch'), printf('%.4f', double_6) AS double_6, string_7, string_8, quote(binary_9), quote(binary_10) FROM no_nulls) TO STDOUT WITH (DELIMITER '|', NULL '');
+EOF