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commit cfd7ee0e520df68c2f16dea4406948ce71dc7dd0
Author: James Turton <ja...@somecomputer.xyz>
AuthorDate: Thu May 6 15:28:18 2021 +0200
Add LMT (last modified time) to the implicit columns returned for files.
---
.../005-querying-a-file-system-introduction.md | 61 +++++++++++-----------
1 file changed, 30 insertions(+), 31 deletions(-)
diff --git
a/_docs/query-data/query-a-file-system/005-querying-a-file-system-introduction.md
b/_docs/query-data/query-a-file-system/005-querying-a-file-system-introduction.md
index c9f4eb8..b45b882 100644
---
a/_docs/query-data/query-a-file-system/005-querying-a-file-system-introduction.md
+++
b/_docs/query-data/query-a-file-system/005-querying-a-file-system-introduction.md
@@ -3,6 +3,7 @@ title: "Querying a File System Introduction"
slug: "Querying a File System Introduction"
parent: "Querying a File System"
---
+
Files and directories are like standard SQL tables to Drill. You can specify a
file system "database" as a prefix in queries when you refer to objects across
databases. In Drill, a file system database consists of a storage plugin name
@@ -22,54 +23,52 @@ more information.
Drill supports the following file types:
- * Plain text files, including:
- * Comma-separated values (CSV, type: text)
- * Tab-separated values (TSV, type: text)
- * Pipe-separated values (PSV, type: text)
- * Structured data files:
- * [Avro]({{site.baseurl}}/docs/querying-avro-files/) (type: avro)
- * [JSON]({{site.baseurl}}/docs/querying-json-files/) (type: json)
- * [Parquet]({{site.baseurl}}/docs/querying-parquet-files/) (type: parquet)
+- Plain text files, including:
+ - Comma-separated values (CSV, type: text)
+ - Tab-separated values (TSV, type: text)
+ - Pipe-separated values (PSV, type: text)
+- Structured data files:
+ - [Avro]({{site.baseurl}}/docs/querying-avro-files/) (type: avro)
+ - [JSON]({{site.baseurl}}/docs/querying-json-files/) (type: json)
+ - [Parquet]({{site.baseurl}}/docs/querying-parquet-files/) (type: parquet)
The extensions for these file types must match the configuration settings for
your registered storage plugins. For example, PSV files may be defined with a
-`.tbl` extension, while CSV files are defined with a `.csv` extension.
+`.tbl` extension, while CSV files are defined with a `.csv` extension.
+
+## Implicit Columns
+
+Drill 1.8 introduces implicit columns. Implicit columns provide file
information, such as the directory path to a file and the file extension. You
can query implicit columns in files, directories, nested directories, and files.
+
+The following table lists the implicit columns available and their
descriptions:
-## Implicit Columns
-Drill 1.8 introduces implicit columns. Implicit columns provide file
information, such as the directory path to a file and the file extension. You
can query implicit columns in files, directories, nested directories, and
files.
+| Implicit Column Name | Description
|
+| -------------------- |
--------------------------------------------------------------------------------------
|
+| FQN | The fully qualified name. Contains the full path to
the file, including the file name. |
+| FILEPATH | The full path to the file, without the file name.
|
+| FILENAME | The file name with the file extension. Does not
include the path to the file. |
+| SUFFIX | The file suffix without the dot (.) at the beginning.
|
+| LMT | The last modification time of the file as recorded by
the containing file system |
-The following table lists the implicit columns available and their
descriptions:
-
-| Implicit Column Name | Description
|
-|------------------------|--------------------------------------------------------------------------------------------|
-| FQN | The fully qualified name. Contains the full path
to the file, including the file name. |
-| FILEPATH | The full path to the file, without the file name.
|
-| FILENAME | The file name with the file extension. Does not
include the path to the file. |
-| SUFFIX | The file suffix without the dot (.) at the
beginning. |
+To access implicit columns, you must explicitly include the columns in a
query, as shown in the following example:
-To access implicit columns, you must explicitly include the columns in a
query, as shown in the following example:
+ 0: jdbc:drill:zk=local> SELECT fqn, filepath, filename, suffix FROM
dfs.`/dev/data/files/test.csvh` LIMIT 1;
- 0: jdbc:drill:zk=local> SELECT fqn, filepath, filename, suffix FROM
dfs.`/dev/data/files/test.csvh` LIMIT 1;
-
|-------------------------------------|--------------------------|---------------|----------------|
| fqn | filepath |
filename | suffix |
|-------------------------------------|--------------------------|---------------|----------------|
| /dev/data/files/test.csvh | /dev/data/files |
test.csvh | csvh |
-
|-------------------------------------|--------------------------|---------------|----------------|
+
|-------------------------------------|--------------------------|---------------|----------------|
-{% include startnote.html %}If a table has a column with the same name as an
implicit column, such as “suffix,” the implicit column overrides the table
column.{% include endnote.html %}
+{% include startnote.html %}If a table has a column with the same name as an
implicit column, such as “suffix,” the implicit column overrides the table
column.{% include endnote.html %}
-If a column name has the same name as an implicit column, you can change the
default implicit column name using the [ALTER SYSTEM|SESSION
SET]({{site.baseurl}}/docs/alter-system/) command with the appropriate
parameter, as shown in the following example:
+If a column name has the same name as an implicit column, you can change the
default implicit column name using the [ALTER SYSTEM|SESSION
SET]({{site.baseurl}}/docs/alter-system/) command with the appropriate
parameter, as shown in the following example:
- ALTER SYSTEM SET `drill.exec.storage.implicit.suffix.column.label` =
appendix;
+ ALTER SYSTEM SET `drill.exec.storage.implicit.suffix.column.label` =
appendix;
-Use the following configuration options to change the default implicit column
names:
+Use the following configuration options to change the default implicit column
names:
drill.exec.storage.implicit.fqn.column.label
drill.exec.storage.implicit.filepath.column.label
drill.exec.storage.implicit.filename.column.label
drill.exec.storage.implicit.suffix.column.label
-
-
-
-
