[command] add show command and make tail/head string friendly by rmannibucau · Pull Request #163 · hardwood-hq/hardwood

rmannibucau · 2026-03-26T18:58:46Z

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gunnarmorling

Thanks a lot, @rmannibucau! A few comments and suggestions inline.

gunnarmorling · 2026-03-26T19:23:41Z

+    CommandSpec spec;
+    @CommandLine.Option(names = {"-s", "--bytes-as-string"}, defaultValue = "false", description = "Render binaries as string.")
+    boolean bytesAsString;
+    @CommandLine.Option(names = {"-ss", "--sample-size"}, defaultValue = "10", description = "Max number of line used to autoadjust the column width.")


Do we truly need that, can't we not just use all rows. I want to minimize options as much as possible.

use all rows -> quite unlikely until you accept to assign too much gigs to the JVM IMHO, I like to keep it light in memory requirement (streaming), default doesn't require anything so should be ok, it is just to read a few line to try to adjust a bit more (ex: "user agent" vs the actual value which is super wide)

gunnarmorling · 2026-03-26T19:24:12Z

+import java.util.stream.IntStream;
+
+// note: align text left since it is how people do read in english
+public class StreamedTable {


What does "streamed" mean?

streaming, no materialization in memory of the full table

gunnarmorling · 2026-03-26T19:25:44Z

+                        +----+----------------+-----------------+
+                        | id | prefix_strings | varying_strings |
+                        +----+----------------+-----------------+
+                        |  1 |          apple |           hello |
+                        +----+----------------+-----------------+
+                        |  2 |    application |           world |
+                        +----+----------------+-----------------+
+                        |  3 |          apply |       wonderful |
+                        +----+----------------+-----------------+
+                        |  4 |         banana |          wonder |
+                        +----+----------------+-----------------+
+                        |  5 |        bandana |          wander |
+                        +----+----------------+-----------------+
+                        |  6 |           band |       wandering |
+                        +----+----------------+-----------------+
+                        |  7 |      bandwidth |            test |
+                        +----+----------------+-----------------+
+                        |  8 |            ban |         testing |
+                        +----+----------------+-----------------+""");


Can we have line delimiters only after the header row, it reduces the space needed.

Suggested change

+----+----------------+-----------------+

| id | prefix_strings | varying_strings |

+----+----------------+-----------------+

| 1 | apple | hello |

+----+----------------+-----------------+

| 2 | application | world |

+----+----------------+-----------------+

| 3 | apply | wonderful |

+----+----------------+-----------------+

| 4 | banana | wonder |

+----+----------------+-----------------+

| 5 | bandana | wander |

+----+----------------+-----------------+

| 6 | band | wandering |

+----+----------------+-----------------+

| 7 | bandwidth | test |

+----+----------------+-----------------+

| 8 | ban | testing |

+----+----------------+-----------------+""");

+----+----------------+-----------------+

| id | prefix_strings | varying_strings |

+----+----------------+-----------------+

| 1 | apple | hello |

| 2 | application | world |

| 3 | apply | wonderful |

| 4 | banana | wonder |

| 5 | bandana | wander |

| 6 | band | wandering |

| 7 | bandwidth | test |

| 8 | ban | testing |

+----+----------------+-----------------+""");

did you try with yellow taxi or a table which is way wider? you have no idea on which line you are so yes it is doable but something more fancy can be desired no?

adding a boolean to enable this mode for now, kept the delimiter by default but we can swtch it later on

ultimately we can see to reuse https://tomitribe.github.io/crest/tables/border-styles/ (extracting this part in a reusable lib)
I can envision a ~/.hardwoodrc for this kind of thing

gunnarmorling · 2026-03-26T19:27:12Z

+    default Iterator<RowReader> toIterator() {
+        return new Iterator<>() {
+            @Override
+            public boolean hasNext() {
+                return RowReader.this.hasNext();
+            }
+
+            @Override
+            public RowReader next() {
+                RowReader.this.next();
+                return RowReader.this;
+            }
+        };
+    }
+
+    /// Convenient method to convert this to a Stream.
+    default Stream<RowReader> toStream() {
+        return StreamSupport.stream(Spliterators.spliteratorUnknownSize(toIterator(), Spliterator.IMMUTABLE), false);
+    }


Can we have these as internal methods where you need them for now. I want to keep the public API as minimal as possible.

what about making the row reader an actual Iterator, it is weird it is 95% of it only? will drop it for now

rmannibucau · 2026-03-26T22:24:37Z

@gunnarmorling addressed comments where it was possible, main pending point will be about the delimiter for tables but my sample files are messed up (one row takes like 4 lines on the screen) without and it is hard to know where I am without the delimiter so I'm mixed about this one

rmannibucau · 2026-03-27T09:04:53Z

reversed the table style but kept the toggle since it is what makes it usable for now - we might envision to replace it by an empty line or another separator but when data are very wide and needs to not be truncated an option is needed

gunnarmorling · 2026-03-27T21:02:20Z

Could you rebase this one to latest main, now that #144 has been resolved? Thanks a lot.

rmannibucau · 2026-03-28T17:42:46Z

@gunnarmorling rebased

gunnarmorling · 2026-03-31T09:24:17Z

Thanks a lot, @rmannibucau! I've rebased this once more and done a range of follow-up changes via #216, which is based on your work. It expands help and docs, introduces the "ALL" sentinel value for the -n flag, adds test for --transpose, and adds projection support. Gonna close this PR in favor of #216. I've also logged #214 as a follow-up.

This was referenced Mar 26, 2026

CLI: STRING columns display as <N bytes> instead of text #159

Closed

Will CLI support a parquet query language or alike? #164

Open

gunnarmorling reviewed Mar 26, 2026

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rmannibucau force-pushed the dev/show-command-and-friends branch from 64b6323 to dca4282 Compare March 26, 2026 22:23

gunnarmorling reviewed Mar 27, 2026

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Comment thread cli/src/main/java/dev/hardwood/command/ConvertCommand.java Outdated

Comment thread s3/src/main/java/dev/hardwood/s3/S3InputFile.java Outdated

Comment thread cli/src/test/java/dev/hardwood/command/PrintCommandTest.java Outdated

rmannibucau added 6 commits March 28, 2026 18:38

rebase

b105753

[command] merge head/tail/show commands

9d5ca23

[command] enable to drop the row line separator

549ec84

rebase

64c5c91

cleanup

aef10b8

better test style

dcb3aa6

rmannibucau force-pushed the dev/show-command-and-friends branch from 8cbc7f4 to dcb3aa6 Compare March 28, 2026 17:38

rebase

2cb6a29

gunnarmorling closed this Mar 31, 2026

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rmannibucau Mar 26, 2026 •

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gunnarmorling commented Mar 31, 2026 •

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