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feat(DQL): @groupby on scalar fields and count duplicate (#7746) #8550

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feat(DQL): @groupby on scalar fields and count duplicate (#7746) #8550

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62 changes: 50 additions & 12 deletions query/groupby.go
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Original file line number Diff line number Diff line change
Expand Up @@ -285,11 +285,14 @@ func (sg *SubGraph) fillGroupedVars(doneVars map[string]varValue, path []*SubGra

var pathNode *SubGraph
var dedupMap dedup

// uidPredicate is true when atleast one argument to
// the groupby is uid predicate.
uidPredicate := false
for _, child := range sg.Children {
if !child.Params.IgnoreResult {
continue
}
uidPredicate = uidPredicate || !child.DestMap.IsEmpty()

attr := child.Params.Alias
if attr == "" {
Expand All @@ -307,6 +310,23 @@ func (sg *SubGraph) fillGroupedVars(doneVars map[string]varValue, path []*SubGra
pathNode = child
} else {
// It's a value node.

// Currently vars are supported only at the root.
// for eg, The following query will result into error:-
// v as var(func: uid(1,31)) {
// name
// friend @groupby(age) {
// a as count(uid)
// }
// }
// since `a` is a global variable which stores (uid, val) pair for
// all the srcUids (1 & 31 in this case), we can't store distinct
// vals for same uid locally. This will eventually lead to incorrect
// results.
if sg.SrcFunc == nil {
return errors.Errorf("Vars can be assigned only at root when grouped by Value")
}

for i, v := range child.valueMatrix {
srcUid := child.SrcUIDs.Uids[i]
if len(v.Values) == 0 {
Expand Down Expand Up @@ -347,17 +367,35 @@ func (sg *SubGraph) fillGroupedVars(doneVars map[string]varValue, path []*SubGra
if len(grp.keys) == 0 {
continue
}
if len(grp.keys) > 1 {
return errors.Errorf("Expected one UID for var in groupby but got: %d", len(grp.keys))
}
uidVal := grp.keys[0].key.Value
uid, ok := uidVal.(uint64)
if !ok {
return errors.Errorf("Vars can be assigned only when grouped by UID attribute")
}
// grp.aggregates could be empty if schema conversion failed during aggregation
if len(grp.aggregates) > 0 {
tempMap[uid] = grp.aggregates[len(grp.aggregates)-1].key

if len(grp.keys) == 1 && grp.keys[0].key.Tid == types.UidID {
uidVal := grp.keys[0].key.Value
uid, _ := uidVal.(uint64)
// grp.aggregates could be empty if schema conversion failed during aggregation
if len(grp.aggregates) > 0 {
tempMap[uid] = grp.aggregates[len(grp.aggregates)-1].key
}
} else {
// if there are more than one predicates or a single scalar
// predicate in the @groupby then the variable stores the mapping of
// uid -> count of duplicates. for eg if there are two predicates(u & v) and
// the grouped uids for (u1, v1) pair are (uid1, uid2, uid3) then the variable
// stores (uid1, 3), (uid2, 3) & (uid2, 2) map.
// For the query given below:-
// var(func: type(Student)) @groupby(school, age) {
// c as count(uid)
// }
// if the grouped result is:-
// (s1, age1) -> "0x1", "0x2", "0x3"
// (s2, age2) -> "0x4"
// (s3, ag3) -> "0x5","0x6"
// then `c` will store the mapping:-
// {"0x1" -> 3, "0x2" -> 3, "0x3" -> 3, "0x4" -> 1, "0x5" -> 2, "0x6"-> 2}
for _, uid := range grp.uids {
if len(grp.aggregates) > 0 {
tempMap[uid] = grp.aggregates[len(grp.aggregates)-1].key
}
}
}
}
doneVars[chVar] = varValue{
Expand Down
64 changes: 64 additions & 0 deletions query/query0_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1498,6 +1498,70 @@ func TestGroupByRootAlias(t *testing.T) {
require.JSONEq(t, `{"data":{"me":[{"@groupby":[{"age":17,"Count":1},{"age":19,"Count":1},{"age":38,"Count":1},{"age":15,"Count":2}]}]}}`, js)
}

func TestGroupByCountValVar(t *testing.T) {
query := `
{
var(func: uid(1, 23, 24, 25, 31)) @groupby(age) {
c as count(uid)
}
me(func: uid(c)) {
uid
val: val(c)
}
}
`
js := processQueryNoErr(t, query)
require.JSONEq(t, `{"data":{"me":[{"uid": "0x1","val":1},{"uid": "0x17","val": 2},{"uid": "0x18","val": 2},{"uid": "0x19","val": 1},{"uid": "0x1f","val": 1}]}}`, js)
}

func TestGroupByCountValVarFilter(t *testing.T) {
query := `
{
var(func: uid(1, 23, 24, 25, 31)) @groupby(age) {
c as count(uid)
}
me(func: uid(c)) @filter(ge(val(c),2)) {
name
val: val(c)
}
}
`
js := processQueryNoErr(t, query)
require.JSONEq(t, `{"data":{"me": [{"name": "Rick Grimes","val": 2},{"name": "Glenn Rhee","val": 2}]}}`, js)
}

func TestGroupByMultiCountValVar(t *testing.T) {
query := `
{
var(func: uid(1, 23, 24, 25, 31)) @groupby(name,age) {
c as count(uid)
}
me(func: uid(c)) {
name
val: val(c)
}
}
`
js := processQueryNoErr(t, query)
require.JSONEq(t, `{"data": {"me": [{"name": "Michonne","val": 1},{"name": "Rick Grimes","val": 1},{"name": "Glenn Rhee","val": 1},{"name": "Daryl Dixon","val": 1},{"name": "Andrea","val": 1}]}}`, js)
}

func TestGroupByCountUidValVar(t *testing.T) {
query := `
{
var(func: uid(1, 23, 24)) @groupby(school, age) {
c as count(uid)
}
me(func: uid(c)) {
name
val: val(c)
}
}
`
js := processQueryNoErr(t, query)
require.JSONEq(t, `{"data": {"me": [{"name": "Michonne","val": 1},{"name": "Rick Grimes","val": 1},{"name": "Glenn Rhee","val": 1}]}}`, js)
}

func TestGroupByRootAlias2(t *testing.T) {
query := `
{
Expand Down