[Metrics][Discover] Discover to prefer line chars for time series data

src/platform/packages/shared/kbn-esql-utils/index.ts

@@ -52,6 +52,7 @@ export {
   constructCascadeQuery,
   mutateQueryStatsGrouping,
   appendFilteringWhereClauseForCascadeLayout,
+  hasTimeseriesBucketAggregation,
 } from './src';
 
 export { ENABLE_ESQL, FEEDBACK_LINK } from './constants';

src/platform/packages/shared/kbn-esql-utils/src/index.ts

@@ -28,6 +28,7 @@ export {
   getKqlSearchQueries,
   getRemoteClustersFromESQLQuery,
   convertTimeseriesCommandToFrom,
+  hasTimeseriesBucketAggregation,
 } from './utils/query_parsing_helpers';
 export { getIndexPatternFromESQLQuery } from './utils/get_index_pattern_from_query';
 export { queryCannotBeSampled } from './utils/query_cannot_be_sampled';

src/platform/packages/shared/kbn-esql-utils/src/utils/query_parsing_helpers.test.ts

@@ -31,6 +31,7 @@ import {
   convertTimeseriesCommandToFrom,
   hasLimitBeforeAggregate,
   missingSortBeforeLimit,
+  hasTimeseriesBucketAggregation,
 } from './query_parsing_helpers';
 
 describe('esql query helpers', () => {
@@ -1052,4 +1053,112 @@ describe('esql query helpers', () => {
       expect(missingSortBeforeLimit('FROM index | LIMIT 10 | SORT field')).toBe(true);
     });
   });
+
+  describe('hasTimeseriesBucketAggregation', () => {
+    const mockColumns = [
+      {
+        id: 'BUCKET(@timestamp, 1h)',
+        isNull: false,
+        meta: { type: 'date', esType: 'date' },
+        name: 'BUCKET(@timestamp, 1h)',
+      },
+      {
+        id: 'agent.name',
+        isNull: false,
+        meta: { type: 'string', esType: 'keyword' },
+        name: 'agent.name',
+      },
+      {
+        id: '@timestamp',
+        isNull: false,
+        meta: { type: 'date', esType: 'date' },
+        name: '@timestamp',
+      },
+      {
+        id: 'c3',
+        isNull: false,
+        meta: { type: 'number', esType: 'long' },
+        name: 'c3',
+      },
+    ] as DatatableColumn[];
+
+    it('should return false if the query is empty', () => {
+      expect(hasTimeseriesBucketAggregation('')).toBe(false);
+    });
+    it('should return false if it is not a timeseries command', () => {
+      expect(
+        hasTimeseriesBucketAggregation('FROM index | STATS COUNT() BY bucket(@timestamp, 1h)')
+      ).toBe(false);
+    });
+    it('should return false if there is no bucket aggregation', () => {
+      expect(hasTimeseriesBucketAggregation('TS index | STATS COUNT() BY @timestamp')).toBe(false);
+    });
+    it('should return false if the bucket aggregation is not a date column', () => {
+      expect(
+        hasTimeseriesBucketAggregation(
+          'TS index | STATS COUNT() BY bucket(c3, 20, 100, 200), agent.name',
+          mockColumns
+        )
+      ).toBe(false);
+    });
+    it('should return false if bucket column cannot be identified', () => {
+      expect(
+        hasTimeseriesBucketAggregation('TS index | STATS COUNT() BY bucket(@timestamp, 1h)')
+      ).toBe(false);
+    });
+    it('should return false if the last stats command does not contain a bucket aggregation', () => {
+      expect(
+        hasTimeseriesBucketAggregation(
+          `TS index 
+            | STATS count_per_day=COUNT(*) BY category=CATEGORIZE(message), @timestamp=BUCKET(@timestamp, 1 day) 
+            | STATS count = SUM(count_per_day), Trend=VALUES(count_per_day) BY category
+            | KEEP category, count
+            | STATS sample = SAMPLE(count, 10) BY category`,
+          mockColumns
+        )
+      ).toBe(false);
+    });
+    it('should return true if the query contains a bucket aggregation', () => {
+      expect(
+        hasTimeseriesBucketAggregation(
+          'TS index | STATS COUNT() BY bucket(@timestamp, 1h)',
+          mockColumns
+        )
+      ).toBe(true);
+    });
+    it('should return true if the query contains aliased bucket aggregation', () => {
+      const columns = [
+        {
+          id: 't',
+          isNull: false,
+          meta: { type: 'date', esType: 'date' },
+          name: 't',
+        },
+      ] as DatatableColumn[];
+
+      expect(
+        hasTimeseriesBucketAggregation(
+          'TS index | STATS COUNT() BY t=bucket(@timestamp, 1h)',
+          columns
+        )
+      ).toBe(true);
+    });
+    it('should return true if the query contains a bucket aggregation with multiple breakdowns', () => {
+      expect(
+        hasTimeseriesBucketAggregation(
+          'TS index | STATS COUNT() BY bucket(@timestamp, 1h), agent.name',
+          mockColumns
+        )
+      ).toBe(true);
+    });
+
+    it('should return true if the query bucket aggregation, case insensitive and ignoring spaces', () => {
+      expect(
+        hasTimeseriesBucketAggregation(
+          'TS index | STATS COUNT() BY BUCKET(@timestamp,    1h), agent.name',
+          mockColumns
+        )
+      ).toBe(true);
+    });
+  });
 });

src/platform/packages/shared/kbn-esql-utils/src/utils/query_parsing_helpers.ts

@@ -591,3 +591,62 @@ export const missingSortBeforeLimit = (esql: string): boolean => {
   }
   return false;
 };
+
+/**
+ * Checks if the ESQL query contains a timeseries bucket aggregation.
+ * @param esql: string - The ESQL query string
+ * @param columns: DatatableColumn[] - The columns of the datatable
+ * @returns true if the query contains a timeseries bucket aggregation, false otherwise
+ */
+export function hasTimeseriesBucketAggregation(
+  esql: string,
+  columns: DatatableColumn[] = []
+): boolean {
+  const { root } = Parser.parse(esql);
+
+  const isTimeseriesCommand = Walker.commands(root).some(({ name }) => name === 'ts');
+  if (!isTimeseriesCommand) {
+    return false;
+  }
+
+  const columnsMap = new Map<string, DatatableColumn>();
+  columns.forEach((column) => {
+    const trimmedId = column.id.trim().replace(/\s+/g, '').toLowerCase();
+    columnsMap.set(trimmedId, column);
+  });
+
+  const statsCommands = Walker.commands(root).filter(({ name }) => name === 'stats');
+  if (statsCommands.length === 0) {
+    return false;
+  }
+
+  const byCommands = Walker.matchAll(statsCommands, { type: 'option', name: 'by' });
+
+  const lastByCommand = byCommands[Math.max(byCommands.length - 1, 0)];
+  const bucketColumns: string[] = [];
+  walk(lastByCommand, {
+    // STATS ... BY someAlias=BUCKET(column, interval), extracts the alias name
+    visitColumn: (node, parent) => {
+      if (isFunctionExpression(parent) && parent.subtype === 'binary-expression') {
+        bucketColumns.push(node.name);
+      }
+    },
+    // STATS ... BY BUCKET(column, interval), extracts the entire BUCKET function
+    visitFunction: (node, parent) => {
+      if (isFunctionExpression(parent) && parent.subtype === 'binary-expression') {
+        return;
+      }
+
+      if (node.subtype === 'variadic-call' && node.name === 'bucket') {
+        bucketColumns.push(node.text.trim().replace(/\s+/g, '').toLowerCase());
+      }
+    },
+  });
+
+  const isDateHistogram = bucketColumns.some((column) => {
+    const columnData = columnsMap.get(column);
+    return columnData?.meta.type === 'date';
+  });
+
+  return isDateHistogram;
+}

src/platform/packages/shared/kbn-unified-histogram/services/lens_vis_service.ts

@@ -16,6 +16,7 @@ import {
   hasTransformationalCommand,
   getCategorizeField,
   convertTimeseriesCommandToFrom,
+  hasTimeseriesBucketAggregation,
 } from '@kbn/esql-utils';
 import type { DataView, DataViewField } from '@kbn/data-views-plugin/common';
 import type {
@@ -657,10 +658,15 @@ export class LensVisService {
       return [];
     }
 
-    const preferredChartType = preferredVisAttributes
+    const mappedPreferredChartType = preferredVisAttributes
       ? mapVisToChartType(preferredVisAttributes.visualizationType)
       : undefined;
 
+    const preferredChartType =
+      !mappedPreferredChartType && hasTimeseriesBucketAggregation(query.esql, columns)
+        ? ChartType.Line
+        : mappedPreferredChartType;
+
     let visAttributes = preferredVisAttributes;
 
     if (preferredVisAttributes) {
@@ -671,7 +677,7 @@ export class LensVisService {
       dataViewSpec: dataView?.toSpec(),
       fieldName: '',
       textBasedColumns: columns,
-      query: query && isOfAggregateQueryType(query) ? query : undefined,
+      query,
     };
 
     return (