mirror of
https://github.com/ClickHouse/ClickHouse.git
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59 lines
2.7 KiB
Python
59 lines
2.7 KiB
Python
#!/usr/bin/env python3
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import os
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import sys
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import random
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import string
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CURDIR = os.path.dirname(os.path.realpath(__file__))
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sys.path.insert(0, os.path.join(CURDIR, 'helpers'))
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from pure_http_client import ClickHouseClient
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def get_random_string(length):
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return ''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(length))
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client = ClickHouseClient()
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def insert_block(table_name, block_granularity_rows, block_rows):
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global client
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block_data = []
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index_granularity_bytes = 10 * 1024 * 1024
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row_bytes = index_granularity_bytes // block_granularity_rows
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for _ in range(block_rows):
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block_data.append(get_random_string(row_bytes - 1))
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values_row = ", ".join("(1, '" + row + "')" for row in block_data)
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client.query("INSERT INTO {} VALUES {}".format(table_name, values_row))
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try:
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client.query("DROP TABLE IF EXISTS t")
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client.query("CREATE TABLE t (v UInt8, data String) ENGINE = MergeTree() ORDER BY tuple() SETTINGS min_bytes_for_wide_part = 0")
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client.query("SYSTEM STOP MERGES t")
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# These blocks size taken from the real table which reproduces the error
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# when we get granule with more rows then fixed granularity after horizontal merge.
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# About 10k rows when max is 8912.
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#
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# Why these blocks are special?
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# 1) The first one contains 1811 rows, but its granule should have 6853.
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# So we write 1811 and get unfinished granule with 6853 - 1811 = 5042 rows to write from the next blocks.
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#
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# 2) The second block has fewer rows than rows left in the unfinished granule (3094 < 5042).
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# It can be written entirely in this unfinished granule and we will still have some rows left. But it's granularity
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# should be smaller than rows left in granule (3094 < 5042), so clickhouse will adjust (make smaller) this last unfinished granule.
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# This adjust logic contained a bug: we adjust not to the new block's granularity (3094), but to the difference of the new block granularity and
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# already written rows (3094 - 1811 = 1283). This lead to several unsigned integer overflows in code and huge granules as result.
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#
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# 3) Last block just triggers the check that each granule has fewer rows than fixed granularity rows. If the bug from 2) exists then it will fail.
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insert_block("t", block_granularity_rows=6853, block_rows=1811)
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insert_block("t", block_granularity_rows=3094, block_rows=3094)
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insert_block("t", block_granularity_rows=6092, block_rows=6092)
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client.query("SYSTEM START MERGES t")
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client.query("OPTIMIZE TABLE t FINAL")
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print(client.query_return_df("SELECT COUNT() as C FROM t FORMAT TabSeparatedWithNames")['C'][0])
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finally:
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client.query("DROP TABLE IF EXISTS t")
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