Merge pull request #14522 from ClickHouse/formats-dont-skip-bom-in-constructor

More consistent invocation of skipBOMIfExists

src/Processors/Formats/Impl/JSONEachRowRowInputFormat.cpp

@@ -32,9 +32,6 @@ JSONEachRowRowInputFormat::JSONEachRowRowInputFormat(
     ReadBuffer & in_, const Block & header_, Params params_, const FormatSettings & format_settings_)
     : IRowInputFormat(header_, in_, std::move(params_)), format_settings(format_settings_), name_map(header_.columns())
 {
-    /// In this format, BOM at beginning of stream cannot be confused with value, so it is safe to skip it.
-    skipBOMIfExists(in);
-
     size_t num_columns = getPort().getHeader().columns();
     for (size_t i = 0; i < num_columns; ++i)
     {
@@ -285,6 +282,9 @@ void JSONEachRowRowInputFormat::resetParser()
 
 void JSONEachRowRowInputFormat::readPrefix()
 {
+    /// In this format, BOM at beginning of stream cannot be confused with value, so it is safe to skip it.
+    skipBOMIfExists(in);
+
     skipWhitespaceIfAny(in);
     if (!in.eof() && *in.position() == '[')
     {

src/Processors/Formats/Impl/TSKVRowInputFormat.cpp

@@ -19,10 +19,6 @@ namespace ErrorCodes
 TSKVRowInputFormat::TSKVRowInputFormat(ReadBuffer & in_, Block header_, Params params_, const FormatSettings & format_settings_)
     : IRowInputFormat(std::move(header_), in_, std::move(params_)), format_settings(format_settings_), name_map(header_.columns())
 {
-    /// In this format, we assume that column name cannot contain BOM,
-    ///  so BOM at beginning of stream cannot be confused with name of field, and it is safe to skip it.
-    skipBOMIfExists(in);
-
     const auto & sample_block = getPort().getHeader();
     size_t num_columns = sample_block.columns();
     for (size_t i = 0; i < num_columns; ++i)
@@ -30,6 +26,14 @@ TSKVRowInputFormat::TSKVRowInputFormat(ReadBuffer & in_, Block header_, Params p
 }
 
 
+void TSKVRowInputFormat::readPrefix()
+{
+    /// In this format, we assume that column name cannot contain BOM,
+    ///  so BOM at beginning of stream cannot be confused with name of field, and it is safe to skip it.
+    skipBOMIfExists(in);
+}
+
+
 /** Read the field name in the `tskv` format.
   * Return true if the field is followed by an equal sign,
   *  otherwise (field with no value) return false.

src/Processors/Formats/Impl/TSKVRowInputFormat.h

@@ -27,6 +27,7 @@ public:
 
     String getName() const override { return "TSKVRowInputFormat"; }
 
+    void readPrefix() override;
     bool readRow(MutableColumns & columns, RowReadExtension &) override;
     bool allowSyncAfterError() const override { return true; }
     void syncAfterError() override;

src/Processors/Formats/Impl/ValuesBlockInputFormat.cpp

@@ -35,12 +35,13 @@ ValuesBlockInputFormat::ValuesBlockInputFormat(ReadBuffer & in_, const Block & h
           attempts_to_deduce_template(num_columns), attempts_to_deduce_template_cached(num_columns),
           rows_parsed_using_template(num_columns), templates(num_columns), types(header_.getDataTypes())
 {
-    /// In this format, BOM at beginning of stream cannot be confused with value, so it is safe to skip it.
-    skipBOMIfExists(buf);
 }
 
 Chunk ValuesBlockInputFormat::generate()
 {
+    if (total_rows == 0)
+        readPrefix();
+
     const Block & header = getPort().getHeader();
     MutableColumns columns = header.cloneEmptyColumns();
     block_missing_values.clear();
@@ -405,6 +406,12 @@ bool ValuesBlockInputFormat::shouldDeduceNewTemplate(size_t column_idx)
     return false;
 }
 
+void ValuesBlockInputFormat::readPrefix()
+{
+    /// In this format, BOM at beginning of stream cannot be confused with value, so it is safe to skip it.
+    skipBOMIfExists(buf);
+}
+
 void ValuesBlockInputFormat::readSuffix()
 {
     if (buf.hasUnreadData())

src/Processors/Formats/Impl/ValuesBlockInputFormat.h

@@ -63,6 +63,7 @@ private:
 
     bool shouldDeduceNewTemplate(size_t column_idx);
 
+    void readPrefix();
     void readSuffix();
 
     bool skipToNextRow(size_t min_chunk_bytes = 0, int balance = 0);