From 8cbb01b2f5593faae237fb3cc75d370f2ddbc1ee Mon Sep 17 00:00:00 2001
From: Przemek Delewski <pdelewski@quesma.com>
Date: Thu, 9 May 2024 10:37:57 +0200
Subject: [PATCH] Generalizing sql query processing

---
 quesma/clickhouse/quesma_communicator.go | 26 +++++++---------------
 quesma/model/query.go                    | 28 +++++++++++++++++++++---
 quesma/quesma/search.go                  |  2 +-
 quesma/quesma/termsenum/terms_enum.go    |  2 +-
 4 files changed, 35 insertions(+), 23 deletions(-)

diff --git a/quesma/clickhouse/quesma_communicator.go b/quesma/clickhouse/quesma_communicator.go
index 0a6e01e25..668d77d83 100644
--- a/quesma/clickhouse/quesma_communicator.go
+++ b/quesma/clickhouse/quesma_communicator.go
@@ -36,13 +36,11 @@ func (lm *LogManager) ProcessSelectQuery(ctx context.Context, table *Table, quer
 	if err != nil {
 		return nil, err
 	}
-	rows, err := executeQuery(ctx, lm, table.Name, query.StringFromColumns(colNames), append(colNames, query.NonSchemaFields...), rowToScan)
-	if err == nil {
-		for _, row := range rows {
-			row.Index = table.Name
-		}
+	resultColumns, err := table.extractColumns(query, true)
+	if err != nil {
+		return nil, err
 	}
-	return rows, err
+	return executeQuery(ctx, lm, table.Name, query.StringFromColumns(colNames), resultColumns, rowToScan)
 }
 
 // TODO add support for autocomplete for attributes, if we'll find it needed
@@ -114,22 +112,14 @@ func executeQuery(ctx context.Context, lm *LogManager, tableName string, queryAs
 	return res, err
 }
 
-func (lm *LogManager) ProcessAutocompleteSuggestionsQuery(ctx context.Context, table *Table, query *model.Query) ([]model.QueryResultRow, error) {
+func (lm *LogManager) ProcessQuery(ctx context.Context, table *Table, query *model.Query) ([]model.QueryResultRow, error) {
 	colNames, err := table.extractColumns(query, false)
 	if err != nil {
 		return nil, err
 	}
-	rowToScan := make([]interface{}, len(colNames)+len(query.NonSchemaFields))
-	return executeQuery(ctx, lm, table.Name, query.String(), query.Fields, rowToScan)
-}
-
-func (lm *LogManager) ProcessGeneralAggregationQuery(ctx context.Context, table *Table, query *model.Query) ([]model.QueryResultRow, error) {
-	colNames, err := table.extractColumns(query, true)
-	if err != nil {
-		return nil, err
-	}
-	rowToScan := make([]interface{}, len(colNames))
-	return executeQuery(ctx, lm, table.Name, query.String(), colNames, rowToScan)
+	rowToScanLen := len(colNames) + len(query.NonSchemaFields)
+	rowToScan := make([]interface{}, rowToScanLen)
+	return executeQuery(ctx, lm, table.Name, query.StringFromColumns(colNames), colNames, rowToScan)
 }
 
 // 'selectFields' are all values that we return from the query, both columns and non-schema fields,
diff --git a/quesma/model/query.go b/quesma/model/query.go
index 9797da988..0021114f6 100644
--- a/quesma/model/query.go
+++ b/quesma/model/query.go
@@ -91,11 +91,14 @@ func (q *Query) String() string {
 func (q *Query) StringFromColumns(colNames []string) string {
 	var sb strings.Builder
 	sb.WriteString("SELECT ")
+	if q.IsDistinct {
+		sb.WriteString("DISTINCT ")
+	}
 	for i, field := range colNames {
-		if field != EmptyFieldSelection {
-			sb.WriteString(strconv.Quote(field))
-		} else {
+		if field == "*" || field == EmptyFieldSelection {
 			sb.WriteString(field)
+		} else {
+			sb.WriteString(strconv.Quote(field))
 		}
 		if i < len(colNames)-1 || len(q.NonSchemaFields) > 0 {
 			sb.WriteString(", ")
@@ -112,6 +115,25 @@ func (q *Query) StringFromColumns(colNames []string) string {
 		where = ""
 	}
 	sb.WriteString(" FROM " + q.FromClause + where + q.WhereClause + " " + strings.Join(q.SuffixClauses, " "))
+	if len(q.GroupByFields) > 0 {
+		sb.WriteString(" GROUP BY (")
+		for i, field := range q.GroupByFields {
+			sb.WriteString(field)
+			if i < len(q.GroupByFields)-1 {
+				sb.WriteString(", ")
+			}
+		}
+		sb.WriteString(")")
+
+		sb.WriteString(" ORDER BY (")
+		for i, field := range q.GroupByFields {
+			sb.WriteString(field)
+			if i < len(q.GroupByFields)-1 {
+				sb.WriteString(", ")
+			}
+		}
+		sb.WriteString(")")
+	}
 	return sb.String()
 }
 
diff --git a/quesma/quesma/search.go b/quesma/quesma/search.go
index 7dd3767c5..6c95ce4a5 100644
--- a/quesma/quesma/search.go
+++ b/quesma/quesma/search.go
@@ -543,7 +543,7 @@ func (q *QueryRunner) searchAggregationWorkerCommon(ctx context.Context, aggrega
 	for _, agg := range aggregations {
 		logger.InfoWithCtx(ctx).Msg(agg.String()) // I'd keep for now until aggregations work fully
 		sqls += agg.Query.String() + "\n"
-		rows, err := q.logManager.ProcessGeneralAggregationQuery(dbQueryCtx, table, &agg.Query)
+		rows, err := q.logManager.ProcessQuery(dbQueryCtx, table, &agg.Query)
 		if err != nil {
 			logger.ErrorWithCtx(ctx).Msg(err.Error())
 			continue
diff --git a/quesma/quesma/termsenum/terms_enum.go b/quesma/quesma/termsenum/terms_enum.go
index 32753d279..97f236830 100644
--- a/quesma/quesma/termsenum/terms_enum.go
+++ b/quesma/quesma/termsenum/terms_enum.go
@@ -37,7 +37,7 @@ func handleTermsEnumRequest(ctx context.Context, reqBody []byte, qt *queryparser
 	dbQueryCtx, cancel := context.WithCancel(ctx)
 	// TODO this will be used to cancel goroutine that is executing the query
 	_ = cancel
-	if rows, err2 := qt.ClickhouseLM.ProcessAutocompleteSuggestionsQuery(dbQueryCtx, qt.Table, selectQuery); err2 != nil {
+	if rows, err2 := qt.ClickhouseLM.ProcessQuery(dbQueryCtx, qt.Table, selectQuery); err2 != nil {
 		logger.Error().Msgf("terms enum failed - error processing SQL query [%s]", err2)
 		result, err = json.Marshal(emptyTermsEnumResponse())
 	} else {