diff --git a/parquet-generator/create-pg-db b/parquet-generator/create-pg-db
index 48f476a..05e23df 100755
--- a/parquet-generator/create-pg-db
+++ b/parquet-generator/create-pg-db
@@ -34,7 +34,7 @@ COPY nulls FROM '$here/nulls.csv';
 
 CREATE OR REPLACE FUNCTION quote(TEXT) RETURNS TEXT AS \$\$
   BEGIN
-    RETURN \$1;
+    RETURN CASE WHEN \$1 IS NULL THEN 'NULL' ELSE \$1 END;
   END;
 \$\$ LANGUAGE 'plpgsql' IMMUTABLE;
 
diff --git a/tests/create-query b/tests/create-query
new file mode 100755
index 0000000..40b49cb
--- /dev/null
+++ b/tests/create-query
@@ -0,0 +1,10 @@
+#!/bin/bash
+
+set -euo pipefail
+
+query=${1:?must provide query}
+
+echo "$query"
+psql parquet postgres <<EOF
+COPY ($query) TO STDOUT WITH (DELIMITER '|', NULL '');
+EOF
diff --git a/tests/queries/009-rowid-group-by.sql b/tests/queries/009-rowid-group-by.sql
new file mode 100644
index 0000000..566e69b
--- /dev/null
+++ b/tests/queries/009-rowid-group-by.sql
@@ -0,0 +1,11 @@
+select rowid % 10, count(*) from nulls group by 1 order by 1
+0|10
+1|10
+2|10
+3|10
+4|10
+5|10
+6|10
+7|10
+8|10
+9|10
diff --git a/tests/queries/010-order-by-string7.sql b/tests/queries/010-order-by-string7.sql
new file mode 100644
index 0000000..03171c8
--- /dev/null
+++ b/tests/queries/010-order-by-string7.sql
@@ -0,0 +1,101 @@
+select string_7 from no_nulls1 order by string_7
+0
+1
+10
+11
+12
+13
+14
+15
+16
+17
+18
+19
+2
+20
+21
+22
+23
+24
+25
+26
+27
+28
+29
+3
+30
+31
+32
+33
+34
+35
+36
+37
+38
+39
+4
+40
+41
+42
+43
+44
+45
+46
+47
+48
+49
+5
+50
+51
+52
+53
+54
+55
+56
+57
+58
+59
+6
+60
+61
+62
+63
+64
+65
+66
+67
+68
+69
+7
+70
+71
+72
+73
+74
+75
+76
+77
+78
+79
+8
+80
+81
+82
+83
+84
+85
+86
+87
+88
+89
+9
+90
+91
+92
+93
+94
+95
+96
+97
+98
+99
diff --git a/tests/queries/011-order-by-string8.sql b/tests/queries/011-order-by-string8.sql
new file mode 100644
index 0000000..ee7e347
--- /dev/null
+++ b/tests/queries/011-order-by-string8.sql
@@ -0,0 +1,101 @@
+select string_8 from no_nulls1 order by string_8
+000
+001
+002
+003
+004
+005
+006
+007
+008
+009
+010
+011
+012
+013
+014
+015
+016
+017
+018
+019
+020
+021
+022
+023
+024
+025
+026
+027
+028
+029
+030
+031
+032
+033
+034
+035
+036
+037
+038
+039
+040
+041
+042
+043
+044
+045
+046
+047
+048
+049
+050
+051
+052
+053
+054
+055
+056
+057
+058
+059
+060
+061
+062
+063
+064
+065
+066
+067
+068
+069
+070
+071
+072
+073
+074
+075
+076
+077
+078
+079
+080
+081
+082
+083
+084
+085
+086
+087
+088
+089
+090
+091
+092
+093
+094
+095
+096
+097
+098
+099
diff --git a/tests/queries/012-string-7-is-null.sql b/tests/queries/012-string-7-is-null.sql
new file mode 100644
index 0000000..7abd698
--- /dev/null
+++ b/tests/queries/012-string-7-is-null.sql
@@ -0,0 +1,51 @@
+select rowid, bool_0, quote(binary_10) from nulls where string_7 is null
+10||NULL
+11||NULL
+12||NULL
+13||NULL
+14||NULL
+15||NULL
+16||NULL
+17||NULL
+18||NULL
+19||NULL
+21|0|X'15'
+23|0|X'17'
+25|0|X'19'
+27|0|X'1B'
+29|0|X'1D'
+31|0|X'1F'
+33|0|X'21'
+35|0|X'23'
+37|0|X'25'
+39|0|X'27'
+41|0|X'29'
+43|0|X'2B'
+45|0|X'2D'
+47|0|X'2F'
+49|0|X'31'
+51|0|X'33'
+53|0|X'35'
+55|0|X'37'
+57|0|X'39'
+59|0|X'3B'
+61|0|X'3D'
+63|0|X'3F'
+65|0|X'41'
+67|0|X'43'
+69|0|X'45'
+71|0|X'47'
+73|0|X'49'
+75|0|X'4B'
+77|0|X'4D'
+79|0|X'4F'
+81|0|X'51'
+83|0|X'53'
+85|0|X'55'
+87|0|X'57'
+89|0|X'59'
+91|0|X'5B'
+93|0|X'5D'
+95|0|X'5F'
+97|0|X'61'
+99|0|X'63'
diff --git a/tests/queries/013-string-7-is-not-null.sql b/tests/queries/013-string-7-is-not-null.sql
new file mode 100644
index 0000000..ad0ccca
--- /dev/null
+++ b/tests/queries/013-string-7-is-not-null.sql
@@ -0,0 +1,51 @@
+select rowid, bool_0, quote(binary_10) from nulls where string_7 is not null
+0|1|X'00'
+1|0|X'01'
+2|1|X'02'
+3|0|X'03'
+4|1|X'04'
+5|0|X'05'
+6|1|X'06'
+7|0|X'07'
+8|1|X'08'
+9|0|X'09'
+20||NULL
+22||NULL
+24||NULL
+26||NULL
+28||NULL
+30||NULL
+32||NULL
+34||NULL
+36||NULL
+38||NULL
+40||NULL
+42||NULL
+44||NULL
+46||NULL
+48||NULL
+50||NULL
+52||NULL
+54||NULL
+56||NULL
+58||NULL
+60||NULL
+62||NULL
+64||NULL
+66||NULL
+68||NULL
+70||NULL
+72||NULL
+74||NULL
+76||NULL
+78||NULL
+80||NULL
+82||NULL
+84||NULL
+86||NULL
+88||NULL
+90||NULL
+92||NULL
+94||NULL
+96||NULL
+98||NULL