feat: to_char expression

[SubhamSinghal]

No description provided.

[shehabgamin]

@SubhamSinghal Thank you so much for this contribution! Exciting progress

[shehabgamin]

We also need to account for array input:

(ColumnarValue::Array(array), ColumnarValue::Array(array))
(ColumnarValue::Array(array), ColumnarValue::Scalar(ScalarValue::Utf8(Some(fmt))))

[SubhamSinghal]

@shehabgamin need some help in fixing rust error

[github-actions]

Gold Data Report

Notes

1. The tables below show the number of true positives (TP), true negatives (TN), false positives (FP), and false negatives (FN) in gold data input processing.
2. A positive input is a valid test case, while a negative input is a test case that is expected to fail.

Commit Information

Commit	Revision	Branch
After	60a2f13	refs/pull/874/merge
Before	92083e4	main

Summary

Commit	TP	TN	FP	FN	Total
After	1898	194	44	379	2515
Before	1893	194	44	384	2515

Details

Gold Data Metrics

Group	File	Commit	TP	TN	FP	FN	Total
spark	data_type.json	After	43	5	0	0	48
		Before	43	5	0	0	48
	expression/case.json	After	5	0	0	0	5
		Before	5	0	0	0	5
	expression/cast.json	After	4	0	0	0	4
		Before	4	0	0	0	4
	expression/current.json	After	2	0	0	0	2
		Before	2	0	0	0	2
	expression/date.json	After	4	0	1	0	5
		Before	4	0	1	0	5
	expression/interval.json	After	346	4	1	0	351
		Before	346	4	1	0	351
	expression/large.json	After	2	0	0	0	2
		Before	2	0	0	0	2
	expression/like.json	After	29	10	0	0	39
		Before	29	10	0	0	39
	expression/misc.json	After	109	5	0	1	115
		Before	109	5	0	1	115
	expression/numeric.json	After	31	6	1	0	38
		Before	31	6	1	0	38
	expression/string.json	After	18	1	0	0	19
		Before	18	1	0	0	19
	expression/timestamp.json	After	7	0	3	0	10
		Before	7	0	3	0	10
	expression/window.json	After	73	0	1	0	74
		Before	73	0	1	0	74
	function/agg.json	After	133	0	0	36	169
		Before	133	0	0	36	169
	function/array.json	After	42	0	0	2	44
		Before	42	0	0	2	44
	function/bitwise.json	After	15	0	0	0	15
		Before	15	0	0	0	15
	function/collection.json	After	12	0	0	0	12
		Before	12	0	0	0	12
	function/conditional.json	After	15	0	0	0	15
		Before	15	0	0	0	15
	function/conversion.json	After	2	0	0	0	2
		Before	2	0	0	0	2
	function/csv.json	After	2	0	0	3	5
		Before	2	0	0	3	5
	function/datetime.json	After	121	0	0	24	145
		Before	121	0	0	24	145
	function/generator.json	After	7	0	0	6	13
		Before	7	0	0	6	13
	function/hash.json	After	5	0	0	2	7
		Before	5	0	0	2	7
	function/json.json	After	7	0	0	13	20
		Before	7	0	0	13	20
	function/lambda.json	After	0	0	0	31	31
		Before	0	0	0	31	31
	function/map.json	After	11	0	0	0	11
		Before	11	0	0	0	11
	function/math.json	After	122	0	0	2	124
		Before	122	0	0	2	124
	function/misc.json	After	31	0	0	22	53
		Before	31	0	0	22	53
	function/predicate.json	After	70	0	0	9	79
		Before	70	0	0	9	79
	function/string.json	After	161	0	0	43	204
		Before	156	0	0	48	204
	function/struct.json	After	2	0	0	0	2
		Before	2	0	0	0	2
	function/url.json	After	9	0	0	1	10
		Before	9	0	0	1	10
	function/variant.json	After	0	0	0	28	28
		Before	0	0	0	28	28
	function/window.json	After	6	0	0	3	9
		Before	6	0	0	3	9
	function/xml.json	After	0	0	0	17	17
		Before	0	0	0	17	17
	plan/ddl_alter_table.json	After	49	14	3	11	77
		Before	49	14	3	11	77
	plan/ddl_alter_view.json	After	5	1	0	0	6
		Before	5	1	0	0	6
	plan/ddl_analyze_table.json	After	17	6	0	0	23
		Before	17	6	0	0	23
	plan/ddl_cache.json	After	4	0	1	0	5
		Before	4	0	1	0	5
	plan/ddl_create_index.json	After	0	0	0	3	3
		Before	0	0	0	3	3
	plan/ddl_create_table.json	After	27	30	8	40	105
		Before	27	30	8	40	105
	plan/ddl_delete_from.json	After	2	1	0	0	3
		Before	2	1	0	0	3
	plan/ddl_describe.json	After	4	0	0	0	4
		Before	4	0	0	0	4
	plan/ddl_drop_index.json	After	0	0	0	2	2
		Before	0	0	0	2	2
	plan/ddl_drop_view.json	After	5	0	0	0	5
		Before	5	0	0	0	5
	plan/ddl_insert_into.json	After	16	1	1	0	18
		Before	16	1	1	0	18
	plan/ddl_insert_overwrite.json	After	9	0	2	0	11
		Before	9	0	2	0	11
	plan/ddl_load_data.json	After	4	0	0	0	4
		Before	4	0	0	0	4
	plan/ddl_merge_into.json	After	8	4	3	0	15
		Before	8	4	3	0	15
	plan/ddl_misc.json	After	9	0	0	1	10
		Before	9	0	0	1	10
	plan/ddl_replace_table.json	After	23	14	7	40	84
		Before	23	14	7	40	84
	plan/ddl_select.json	After	1	0	0	0	1
		Before	1	0	0	0	1
	plan/ddl_show_views.json	After	7	0	0	0	7
		Before	7	0	0	0	7
	plan/ddl_uncache.json	After	2	0	0	0	2
		Before	2	0	0	0	2
	plan/ddl_update.json	After	2	1	0	0	3
		Before	2	1	0	0	3
	plan/error_alter_table.json	After	0	2	0	0	2
		Before	0	2	0	0	2
	plan/error_analyze_table.json	After	0	1	0	0	1
		Before	0	1	0	0	1
	plan/error_create_table.json	After	0	6	0	0	6
		Before	0	6	0	0	6
	plan/error_describe.json	After	0	1	0	0	1
		Before	0	1	0	0	1
	plan/error_join.json	After	0	2	0	0	2
		Before	0	2	0	0	2
	plan/error_load_data.json	After	0	1	0	0	1
		Before	0	1	0	0	1
	plan/error_misc.json	After	0	14	0	0	14
		Before	0	14	0	0	14
	plan/error_order_by.json	After	1	4	0	0	5
		Before	1	4	0	0	5
	plan/error_select.json	After	0	15	0	0	15
		Before	0	15	0	0	15
	plan/error_with.json	After	0	1	0	0	1
		Before	0	1	0	0	1
	plan/plan_alter_view.json	After	0	2	0	0	2
		Before	0	2	0	0	2
	plan/plan_create_view.json	After	0	2	0	0	2
		Before	0	2	0	0	2
	plan/plan_explain.json	After	0	1	1	0	2
		Before	0	1	1	0	2
	plan/plan_group_by.json	After	9	1	0	1	11
		Before	9	1	0	1	11
	plan/plan_hint.json	After	25	0	3	0	28
		Before	25	0	3	0	28
	plan/plan_insert_into.json	After	3	0	0	0	3
		Before	3	0	0	0	3
	plan/plan_insert_overwrite.json	After	2	0	0	0	2
		Before	2	0	0	0	2
	plan/plan_join.json	After	53	2	1	6	62
		Before	53	2	1	6	62
	plan/plan_misc.json	After	15	4	0	10	29
		Before	15	4	0	10	29
	plan/plan_order_by.json	After	15	5	1	10	31
		Before	15	5	1	10	31
	plan/plan_select.json	After	86	15	5	12	118
		Before	86	15	5	12	118
	plan/plan_set_operation.json	After	17	0	0	0	17
		Before	17	0	0	0	17
	plan/plan_with.json	After	6	0	1	0	7
		Before	6	0	1	0	7
	plan/unpivot_join.json	After	4	0	0	0	4
		Before	4	0	0	0	4
	plan/unpivot_select.json	After	14	6	0	0	20
		Before	14	6	0	0	20
	table_schema.json	After	8	6	0	0	14
		Before	8	6	0	0	14

[linhr]

Thanks for the contribution!

You can run the following commands locally for formatting and linting:

• cargo +nightly fmt
• cargo clippy --all-targets --all-features

[Copilot]

Pull Request Overview

This PR implements the to_char expression for formatting numeric values to strings in Spark SQL, enabling conversion of numbers to formatted string representations using format patterns.

• Implementation of the to_char function with support for various numeric format patterns including zero-padding, optional digits, decimal points, grouping separators, and sign indicators
• Addition of comprehensive test coverage through golden test files demonstrating various formatting scenarios
• Integration of the new function into the execution engine with proper registration and type handling

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
python/pysail/tests/spark/function/test_to_char.txt	Test examples showing to_char function behavior with various format patterns
crates/sail-spark-connect/tests/gold_data/function/string.json	Updates golden test expectations from failure to success for to_char test cases
crates/sail-plan/src/extension/function/string/spark_to_char.rs	Core implementation of the SparkToChar function with number formatting logic
crates/sail-plan/src/extension/function/string/mod.rs	Module registration for the new to_char function and format tokens
crates/sail-plan/src/extension/function/string/format_tokens.rs	Token parsing logic for format string patterns
crates/sail-execution/src/codec.rs	Function registration and integration into the execution engine

---

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[linhr]

Nice progress!

Could you merge from main and resolve the conflict in codec.rs? Then we can run the workflow and see how it goes.