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The runtime query builder: ClickHouse and PostgreSQL

Every file of the ClickHouse and PostgreSQL versions side by side, with the lines that differ marked. 4 parameter or column types differ in Go.

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Configuration

sgl.yamldiffers
ClickHouse
PostgreSQL
1version: 1
1version: 1
2
2
3databases:
3databases:
4 - name: pier
4 - name: pier
5 dialect: clickhouse
5 dialect: postgres
6 migrations: db/migrations
6 migrations: db/migrations
7 queries: db/queries
7 queries: db/queries
8 go:
8 go:
9 package: store
9 package: store
10 out: internal/store
10 out: internal/store
11 driver: database/sql

Migrations

db/migrations/0001_lost_property.up.sqldiffers
ClickHouse
PostgreSQL
1CREATE TABLE lost_property (
1CREATE TABLE lost_property (
2 id UInt64,
2 id BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
3 item String,
3 item TEXT NOT NULL,
4 colour String,
4 colour TEXT NOT NULL,
5 found_at String,
5 found_at TEXT NOT NULL,
6 days_held UInt32,
6 days_held BIGINT NOT NULL,
7 claimed Bool DEFAULT false,
7 claimed BOOLEAN NOT NULL DEFAULT false,
8 owner_phone Nullable(String)
8 owner_phone TEXT
9) ENGINE = MergeTree() ORDER BY id;
9);
db/migrations/0001_lost_property.down.sqlidentical
ClickHouse
PostgreSQL
1DROP TABLE lost_property;
1DROP TABLE lost_property;

Queries

HandIndiffers
ClickHouse · db/queries/lost_property.sql
PostgreSQL · db/queries/lost_property.sql
1-- sgl.query(HandIn, exec)
1-- sgl.query(HandIn, exec)
2INSERT INTO lost_property (id, item, colour, found_at, days_held)
2INSERT INTO lost_property (item, colour, found_at, days_held) VALUES ($1, $2, $3, $4);
3VALUES ({id:UInt64}, {item:String}, {colour:String}, {found_at:String}, {days_held:UInt32});
Claimdiffers
ClickHouse · db/queries/lost_property.sql
PostgreSQL · db/queries/lost_property.sql
1-- sgl.query(Claim, asyncexec)
1-- sgl.query(Claim, execrows)
2ALTER TABLE lost_property
2UPDATE lost_property SET claimed = true, owner_phone = $1 WHERE id = $2;
3UPDATE claimed = true, owner_phone = {owner_phone:Nullable(String)}
4WHERE id = {id:UInt64};
SearchUnclaimeddiffers
ClickHouse · db/queries/lost_property.sql
PostgreSQL · db/queries/lost_property.sql
1-- sgl.query(SearchUnclaimed, many, dynamic: runtime)
1-- sgl.query(SearchUnclaimed, many, dynamic: runtime)
2SELECT id, item, colour, found_at, days_held
2SELECT id, item, colour, found_at, days_held
3FROM lost_property
3FROM lost_property
4WHERE claimed = false
4WHERE NOT claimed

What sgl generates

HandIndiffers
ClickHouse
PostgreSQL
1func (queries *Queries) HandIn(ctx context.Context, params HandInParams) error
1func (queries *Queries) HandIn(ctx context.Context, params HandInParams) error
2
2
3type HandInParams struct {
3type HandInParams struct {
4 ID uint64
5 Item string
4 Item string
6 Colour string
5 Colour string
7 FoundAt string
6 FoundAt string
8 DaysHeld uint32
7 DaysHeld int64
9}
8}
Claimdiffers
ClickHouse
PostgreSQL
1func (queries *Queries) Claim(ctx context.Context, params ClaimParams) error
1func (queries *Queries) Claim(ctx context.Context, params ClaimParams) (int64, error)
2
2
3type ClaimParams struct {
3type ClaimParams struct {
4 OwnerPhone *string
4 OwnerPhone *string
5 ID uint64
5 ID int64
6}
6}
SearchUnclaimeddiffers
ClickHouse
PostgreSQL
1func (queries *Queries) SearchUnclaimed() *SearchUnclaimedBuilder
1func (queries *Queries) SearchUnclaimed() *SearchUnclaimedBuilder
2
2
3type SearchUnclaimedRow struct {
3type SearchUnclaimedRow struct {
4 ID uint64 `json:"id"`
4 ID int64 `json:"id"`
5 Item string `json:"item"`
5 Item string `json:"item"`
6 Colour string `json:"colour"`
6 Colour string `json:"colour"`
7 FoundAt string `json:"found_at"`
7 FoundAt string `json:"found_at"`
8 DaysHeld uint32 `json:"days_held"`
8 DaysHeld int64 `json:"days_held"`
9}
9}

The program

example.godiffers
ClickHouse
PostgreSQL
1package main
1package main
2
2
3import (
3import (
4 "context"
4 "context"
5 "database/sql"
5 "database/sql"
6 "errors"
6 "errors"
7 "fmt"
7 "fmt"
8 "io"
8 "io"
9
9
10 "seagull.sh/seagull/examples/clickhouse/014_runtime_builder/internal/store"
10 "seagull.sh/seagull/examples/postgres/014_runtime_builder/internal/store"
11)
11)
12
12
13// run searches the pier's unclaimed lost property. dynamic: runtime turns SearchUnclaimed
13// run searches the pier's unclaimed lost property. dynamic: runtime turns SearchUnclaimed
14// into a builder: Where, OrderBy, Limit and Offset add to the SQL, and All, One or Count
14// into a builder: Where, OrderBy, Limit and Offset add to the SQL, and All, One or Count
15// run it. The base query already has WHERE claimed = false, so each Where is joined with
15// run it. The base query already has WHERE NOT claimed, so each Where is joined with AND,
16// AND, which sgl vet points out as hint Q022. The builder inserts its filters, order and
16// which sgl vet points out as hint Q022. The builder inserts its filters, order and limit
17// limit at the places the query leaves for them, before any LIMIT or trailing semicolon,
17// at the places the query leaves for them, before any LIMIT or trailing semicolon, and
18// and Count replaces the SELECT list with COUNT(*), wrapping the whole query instead when
18// Count replaces the SELECT list with COUNT(*), wrapping the whole query instead when it
19// it groups or is DISTINCT (Q023).
19// groups or is DISTINCT (Q023).
20//
20//
21// The builder is safe with untrusted input. Where and OrderBy accept only the columns the
21// The builder is safe with untrusted input. Where and OrderBy accept only the columns the
22// query selects, so owner_phone, which the table has but the query leaves out, cannot be
22// query selects, so owner_phone, which the table has but the query leaves out, cannot be
23// searched. Operators and directions come from fixed allow-lists, and every value is
23// searched. Operators and directions come from fixed allow-lists, and every value is
24// bound as a parameter, never written into the SQL. A refused input does not panic: the
24// bound as a numbered $N parameter after the base query's own, never written into the
25// terminal returns ErrSglUnknownColumn, ErrSglUnknownOperator or ErrSglUnknownDirection.
25// SQL. A refused input does not panic: the terminal returns ErrSglUnknownColumn,
26//
26// ErrSglUnknownOperator or ErrSglUnknownDirection.
27// Claim is an ALTER TABLE ... UPDATE mutation, so it is asyncexec; the connection sets
28// mutations_sync=2, so the claimed phone is gone from the searches that follow.
29//
27//
30// Takes database (*sql.DB) which is a migrated database.
28// Takes database (*sql.DB) which is a migrated database.
31// Takes output (io.Writer) which receives the searches and the refusals.
29// Takes output (io.Writer) which receives the searches and the refusals.
32//
30//
33// Returns error when a query fails or an unsafe input is not refused.
31// Returns error when a query fails or an unsafe input is not refused.
34func run(ctx context.Context, database *sql.DB, output io.Writer) error {
32func run(ctx context.Context, database *sql.DB, output io.Writer) error {
35 queries := store.New(database)
33 queries := store.New(database)
36
34
37 items := []store.HandInParams{
35 items := []store.HandInParams{
38 {ID: 1, Item: "umbrella", Colour: "red", FoundAt: "the pier", DaysHeld: 40},
36 {Item: "umbrella", Colour: "red", FoundAt: "the pier", DaysHeld: 40},
39 {ID: 2, Item: "sunglasses", Colour: "black", FoundAt: "the beach", DaysHeld: 12},
37 {Item: "sunglasses", Colour: "black", FoundAt: "the beach", DaysHeld: 12},
40 {ID: 3, Item: "bucket and spade", Colour: "red", FoundAt: "the beach", DaysHeld: 3},
38 {Item: "bucket and spade", Colour: "red", FoundAt: "the beach", DaysHeld: 3},
41 {ID: 4, Item: "umbrella", Colour: "blue", FoundAt: "the cafe", DaysHeld: 33},
39 {Item: "umbrella", Colour: "blue", FoundAt: "the cafe", DaysHeld: 33},
42 {ID: 5, Item: "phone", Colour: "black", FoundAt: "the pier", DaysHeld: 1},
40 {Item: "phone", Colour: "black", FoundAt: "the pier", DaysHeld: 1},
43 }
41 }
44 for _, item := range items {
42 for _, item := range items {
45 if err := queries.HandIn(ctx, item); err != nil {
43 if err := queries.HandIn(ctx, item); err != nil {
46 return fmt.Errorf("handing in a %s: %w", item.Item, err)
44 return fmt.Errorf("handing in a %s: %w", item.Item, err)
47 }
45 }
48 }
46 }
49 if err := queries.Claim(ctx, store.ClaimParams{OwnerPhone: new("07700 900123"), ID: 5}); err != nil {
47 if _, err := queries.Claim(ctx, store.ClaimParams{OwnerPhone: new("07700 900123"), ID: 5}); err != nil {
50 return fmt.Errorf("claiming the phone: %w", err)
48 return fmt.Errorf("claiming the phone: %w", err)
51 }
49 }
52
50
53 red, err := queries.SearchUnclaimed().Where("colour", "=", "red").OrderBy("id", "ASC").All(ctx)
51 red, err := queries.SearchUnclaimed().Where("colour", "=", "red").All(ctx)
54 if err != nil {
52 if err != nil {
55 return fmt.Errorf("finding red items: %w", err)
53 return fmt.Errorf("finding red items: %w", err)
56 }
54 }
57 fmt.Fprintln(output, "red:")
55 fmt.Fprintln(output, "red:")
58 printItems(output, red)
56 printItems(output, red)
59
57
60 longest, err := queries.SearchUnclaimed().
58 longest, err := queries.SearchUnclaimed().
61 Where("days_held", ">=", 30).
59 Where("days_held", ">=", 30).
62 OrderBy("days_held", "DESC").
60 OrderBy("days_held", "DESC").
63 Limit(2).
61 Limit(2).
64 All(ctx)
62 All(ctx)
65 if err != nil {
63 if err != nil {
66 return fmt.Errorf("finding long-held items: %w", err)
64 return fmt.Errorf("finding long-held items: %w", err)
67 }
65 }
68 fmt.Fprintln(output, "held 30 days or more, longest first:")
66 fmt.Fprintln(output, "held 30 days or more, longest first:")
69 printItems(output, longest)
67 printItems(output, longest)
70
68
71 umbrellas, err := queries.SearchUnclaimed().Where("item", "=", "umbrella").Count(ctx)
69 umbrellas, err := queries.SearchUnclaimed().Where("item", "=", "umbrella").Count(ctx)
72 if err != nil {
70 if err != nil {
73 return fmt.Errorf("counting umbrellas: %w", err)
71 return fmt.Errorf("counting umbrellas: %w", err)
74 }
72 }
75 fmt.Fprintf(output, "unclaimed umbrellas: %d\n", umbrellas)
73 fmt.Fprintf(output, "unclaimed umbrellas: %d\n", umbrellas)
76
74
77 tautology, err := queries.SearchUnclaimed().Where("item", "=", "' OR '1'='1").All(ctx)
75 tautology, err := queries.SearchUnclaimed().Where("item", "=", "' OR '1'='1").All(ctx)
78 if err != nil {
76 if err != nil {
79 return fmt.Errorf("searching for a quoted value: %w", err)
77 return fmt.Errorf("searching for a quoted value: %w", err)
80 }
78 }
81 fmt.Fprintf(output, "items named ' OR '1'='1: %d, as the value is bound, not run\n", len(tautology))
79 fmt.Fprintf(output, "items named ' OR '1'='1: %d, as the value is bound, not run\n", len(tautology))
82
80
83 attempts := []struct {
81 attempts := []struct {
84 label string
82 label string
85 search *store.SearchUnclaimedBuilder
83 search *store.SearchUnclaimedBuilder
86 }{
84 }{
87 {label: "a column the query does not select", search: queries.SearchUnclaimed().Where("owner_phone", "IS NOT NULL", nil)},
85 {label: "a column the query does not select", search: queries.SearchUnclaimed().Where("owner_phone", "IS NOT NULL", nil)},
88 {label: "SQL in a column name", search: queries.SearchUnclaimed().OrderBy("id; DROP TABLE lost_property", "ASC")},
86 {label: "SQL in a column name", search: queries.SearchUnclaimed().OrderBy("id; DROP TABLE lost_property", "ASC")},
89 {label: "an operator outside the allow-list", search: queries.SearchUnclaimed().Where("colour", "= 'red' OR 1=1 --", "red")},
87 {label: "an operator outside the allow-list", search: queries.SearchUnclaimed().Where("colour", "= 'red' OR 1=1 --", "red")},
90 {label: "a direction outside the allow-list", search: queries.SearchUnclaimed().OrderBy("days_held", "DESC; DROP TABLE lost_property")},
88 {label: "a direction outside the allow-list", search: queries.SearchUnclaimed().OrderBy("days_held", "DESC; DROP TABLE lost_property")},
91 }
89 }
92 for _, attempt := range attempts {
90 for _, attempt := range attempts {
93 _, err := attempt.search.All(ctx)
91 _, err := attempt.search.All(ctx)
94 switch {
92 switch {
95 case errors.Is(err, store.ErrSglUnknownColumn), errors.Is(err, store.ErrSglUnknownOperator), errors.Is(err, store.ErrSglUnknownDirection):
93 case errors.Is(err, store.ErrSglUnknownColumn), errors.Is(err, store.ErrSglUnknownOperator), errors.Is(err, store.ErrSglUnknownDirection):
96 fmt.Fprintf(output, "refused %s: %v\n", attempt.label, err)
94 fmt.Fprintf(output, "refused %s: %v\n", attempt.label, err)
97 case err == nil:
95 case err == nil:
98 return fmt.Errorf("%s: got no error, want a refusal", attempt.label)
96 return fmt.Errorf("%s: got no error, want a refusal", attempt.label)
99 default:
97 default:
100 return fmt.Errorf("%s: got %w, want a refusal", attempt.label, err)
98 return fmt.Errorf("%s: got %w, want a refusal", attempt.label, err)
101 }
99 }
102 }
100 }
103 return nil
101 return nil
104}
102}
105
103
106// printItems writes one line per item.
104// printItems writes one line per item.
107//
105//
108// Takes output (io.Writer) which receives the lines.
106// Takes output (io.Writer) which receives the lines.
109// Takes items ([]store.SearchUnclaimedRow) which are the items to print.
107// Takes items ([]store.SearchUnclaimedRow) which are the items to print.
110func printItems(output io.Writer, items []store.SearchUnclaimedRow) {
108func printItems(output io.Writer, items []store.SearchUnclaimedRow) {
111 for _, item := range items {
109 for _, item := range items {
112 fmt.Fprintf(output, " #%d %s %s, found at %s, held %d days\n", item.ID, item.Colour, item.Item, item.FoundAt, item.DaysHeld)
110 fmt.Fprintf(output, " #%d %s %s, found at %s, held %d days\n", item.ID, item.Colour, item.Item, item.FoundAt, item.DaysHeld)
113 }
111 }
114}
112}

Go type differences

The same SQL types map to different Go types, because each database reports them differently.

QueryFieldClickHousePostgreSQL
HandInparameter days_helduint32int64
Claimparameter iduint64int64
SearchUnclaimedcolumn iduint64int64
SearchUnclaimedcolumn days_helduint32int64