Merge pull request #56859 from Avogar/csv-infer-numbers-from-strings

Allow to infer numbers from strings in CSV format

docs/en/interfaces/formats.md

@@ -478,6 +478,7 @@ The CSV format supports the output of totals and extremes the same way as `TabSe
 - [input_format_csv_allow_whitespace_or_tab_as_delimiter](/docs/en/operations/settings/settings-formats.md/# input_format_csv_allow_whitespace_or_tab_as_delimiter) - Allow to use whitespace or tab as field delimiter in CSV strings. Default value - `false`.
 - [input_format_csv_allow_variable_number_of_columns](/docs/en/operations/settings/settings-formats.md/#input_format_csv_allow_variable_number_of_columns) - allow variable number of columns in CSV format, ignore extra columns and use default values on missing columns. Default value - `false`.
 - [input_format_csv_use_default_on_bad_values](/docs/en/operations/settings/settings-formats.md/#input_format_csv_use_default_on_bad_values) - Allow to set default value to column when CSV field deserialization failed on bad value. Default value - `false`.
+- [input_format_csv_try_infer_numbers_from_strings](/docs/en/operations/settings/settings-formats.md/#input_format_csv_try_infer_numbers_from_strings) - Try to infer numbers from string fields while schema inference. Default value - `false`.
 
 ## CSVWithNames {#csvwithnames}
 

docs/en/interfaces/schema-inference.md

@@ -834,6 +834,27 @@ $$)
 └──────────────┴───────────────┘
 ```
 
+#### CSV settings {#csv-settings}
+
+##### input_format_csv_try_infer_numbers_from_strings
+
+Enabling this setting allows inferring numbers from string values.
+
+This setting is disabled by default.
+
+**Example:**
+
+```sql
+SET input_format_json_try_infer_numbers_from_strings = 1;
+DESC format(CSV, '"42","42.42"');
+```
+```reponse
+┌─name─┬─type──────────────┬─default_type─┬─default_expression─┬─comment─┬─codec_expression─┬─ttl_expression─┐
+│ c1   │ Nullable(Int64)   │              │                    │         │                  │                │
+│ c2   │ Nullable(Float64) │              │                    │         │                  │                │
+└──────┴───────────────────┴──────────────┴────────────────────┴─────────┴──────────────────┴────────────────┘
+```
+
 ### TSV/TSKV {#tsv-tskv}
 
 In TSV/TSKV formats ClickHouse extracts column value from the row according to tabular delimiters and then parses extracted value using

docs/en/operations/settings/settings-formats.md

@@ -1130,6 +1130,13 @@ Result
 a  0  1971-01-01
 ```
 
+## input_format_csv_try_infer_numbers_from_strings {#input_format_csv_try_infer_numbers_from_strings}
+
+If enabled, during schema inference ClickHouse will try to infer numbers from string fields.
+It can be useful if CSV data contains quoted UInt64 numbers.
+
+Disabled by default.
+
 ## Values format settings {#values-format-settings}
 
 ### input_format_values_interpret_expressions {#input_format_values_interpret_expressions}

src/Core/Settings.h

@@ -942,6 +942,7 @@ class IColumn;
     M(UInt64, input_format_max_rows_to_read_for_schema_inference, 25000, "The maximum rows of data to read for automatic schema inference", 0) \
     M(UInt64, input_format_max_bytes_to_read_for_schema_inference, 32 * 1024 * 1024, "The maximum bytes of data to read for automatic schema inference", 0) \
     M(Bool, input_format_csv_use_best_effort_in_schema_inference, true, "Use some tweaks and heuristics to infer schema in CSV format", 0) \
+    M(Bool, input_format_csv_try_infer_numbers_from_strings, false, "Try to infer numbers from string fields while schema inference in CSV format", 0) \
     M(Bool, input_format_tsv_use_best_effort_in_schema_inference, true, "Use some tweaks and heuristics to infer schema in TSV format", 0) \
     M(Bool, input_format_csv_detect_header, true, "Automatically detect header with names and types in CSV format", 0) \
     M(Bool, input_format_csv_allow_whitespace_or_tab_as_delimiter, false, "Allow to use spaces and tabs(\\t) as field delimiter in the CSV strings", 0) \

src/Formats/EscapingRuleUtils.cpp

@@ -303,8 +303,8 @@ DataTypePtr tryInferDataTypeByEscapingRule(const String & field, const FormatSet
                 /// Try to determine the type of value inside quotes
                 auto type = tryInferDataTypeForSingleField(data, format_settings);
 
-                /// If we couldn't infer any type or it's a number or tuple in quotes, we determine it as a string.
-                if (!type || isNumber(removeNullable(type)) || isTuple(type))
+                /// If we couldn't infer any type or it's tuple in quotes or it's a number and csv.try_infer_numbers_from_strings = 0, we determine it as a string.
+                if (!type || isTuple(type) || (isNumber(type) && !format_settings.csv.try_infer_numbers_from_strings))
                     return std::make_shared<DataTypeString>();
 
                 return type;

src/Formats/FormatFactory.cpp

@@ -74,6 +74,7 @@ FormatSettings getFormatSettings(ContextPtr context, const Settings & settings)
     format_settings.csv.allow_whitespace_or_tab_as_delimiter = settings.input_format_csv_allow_whitespace_or_tab_as_delimiter;
     format_settings.csv.allow_variable_number_of_columns = settings.input_format_csv_allow_variable_number_of_columns;
     format_settings.csv.use_default_on_bad_values = settings.input_format_csv_use_default_on_bad_values;
+    format_settings.csv.try_infer_numbers_from_strings = settings.input_format_csv_try_infer_numbers_from_strings;
     format_settings.hive_text.fields_delimiter = settings.input_format_hive_text_fields_delimiter;
     format_settings.hive_text.collection_items_delimiter = settings.input_format_hive_text_collection_items_delimiter;
     format_settings.hive_text.map_keys_delimiter = settings.input_format_hive_text_map_keys_delimiter;

src/Formats/FormatSettings.h

@@ -164,6 +164,7 @@ struct FormatSettings
         bool allow_whitespace_or_tab_as_delimiter = false;
         bool allow_variable_number_of_columns = false;
         bool use_default_on_bad_values = false;
+        bool try_infer_numbers_from_strings = true;
     } csv;
 
     struct HiveText

tests/queries/0_stateless/02916_csv_infer_numbers_from_strings.reference

@@ -0,0 +1,6 @@
+c1	Nullable(Int64)					
+c2	Nullable(Float64)					
+c3	Nullable(Bool)					
+c1	Nullable(String)					
+c2	Nullable(String)					
+c3	Nullable(String)					

tests/queries/0_stateless/02916_csv_infer_numbers_from_strings.sql

@@ -0,0 +1,4 @@
+set input_format_csv_try_infer_numbers_from_strings=1;
+desc format(CSV, '"42","42.42","True"');
+desc format(CSV, '"42","42.42","True"\n"abc","def","ghk"');
+