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https://issues.apache.org/jira/browse/DRILL-7358?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16945229#comment-16945229
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ASF GitHub Bot commented on DRILL-7358:
---------------------------------------
paul-rogers commented on pull request #1867: DRILL-7358: Fix COUNT(*) for empty
text files
URL: https://github.com/apache/drill/pull/1867
Fixes a subtle error when a text file has a header (and so has a
schema), but is in a COUNT(*) query, so that no columns are
projected. Ensures that, in this case, an empty schema is
treated as a valid result set.
Tests: updated CSV tests to include this case.
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> Text reader returns nothing for count queries over empty files
> --------------------------------------------------------------
>
> Key: DRILL-7358
> URL: https://issues.apache.org/jira/browse/DRILL-7358
> Project: Apache Drill
> Issue Type: Bug
> Affects Versions: 1.16.0
> Reporter: Arina Ielchiieva
> Assignee: Paul Rogers
> Priority: Major
> Fix For: 1.17.0
>
>
> If we do count over empty CSV files (with or without headers), there is no
> result.
> Though expecting result is 0.
> Unit tests examples:
> {code}
> @Test
> public void testCount() throws Exception {
> String fileName = "headersOnly.csv";
> try (PrintWriter out = new PrintWriter(new FileWriter(new File(testDir,
> fileName)))) {
> out.print("a,b,c"); // note: no \n in the end
> }
> queryBuilder().sql("SELECT count(1) FROM `dfs.data`.`" + fileName +
> "`").print();
> }
> {code}
> {code}
> @Test
> public void testCount() throws Exception {
> String fileName = "empty.csv";
> File file = new File(testDir, fileName);
> assertTrue(file.createNewFile());
> queryBuilder().sql("SELECT count(1) FROM `dfs.data`.`" + fileName +
> "`").print();
> }
> {code}
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