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Reduce number of "stat" syscalls for MergeTree data parts

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This commit is contained in:
Alexey Milovidov 2019-06-16 23:11:30 +03:00
parent e3b21be1bb
commit 49c4f2ffed
1 changed files with 1 additions and 4 deletions
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5
dbms/src/Storages/MergeTree/MergeTreeReader.cpp
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@ -44,9 +44,6 @@ MergeTreeReader::MergeTreeReader(const String & path,
{
try
{
if (!Poco::File(path).exists())
throw Exception("Part " + path + " is missing", ErrorCodes::NOT_FOUND_EXPECTED_DATA_PART);
for (const NameAndTypePair & column : columns)
addStreams(column.name, *column.type, profile_callback, clock_type);
}
@ -163,7 +160,7 @@ void MergeTreeReader::addStreams(const String & name, const IDataType & type,
if (streams.count(stream_name))
return;
bool data_file_exists = Poco::File(path + stream_name + DATA_FILE_EXTENSION).exists();
bool data_file_exists = data_part->checksums.files.count(path + stream_name + DATA_FILE_EXTENSION);
/** If data file is missing then we will not try to open it.
* It is necessary since it allows to add new column to structure of the table without creating new files for old parts.