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new c832523 [ISSUE #3757] docs: Polish the document 'Design_Query.md'.
(#3758)
c832523 is described below
commit c832523742b52306cfabcee03959a85da62e2e9d
Author: 彭小漪 <[email protected]>
AuthorDate: Sat Jan 15 17:25:44 2022 +0800
[ISSUE #3757] docs: Polish the document 'Design_Query.md'. (#3758)
---
docs/en/Design_Query.md | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/docs/en/Design_Query.md b/docs/en/Design_Query.md
index 983d48d..887a073 100644
--- a/docs/en/Design_Query.md
+++ b/docs/en/Design_Query.md
@@ -12,6 +12,8 @@ The MessageId in RocketMQ has a total length of 16 bytes,
including the broker a
The IndexFile provides the user with the querying service by “Querying
Messages by Message Key”. The IndexFile is stored in
$HOME\store\index${fileName}, and the file name is named after the timestamp at
the time of creation. The file size is fixed, which is 420,000,040 bytes
(40+5million\*4+20million\*20). If the UNIQ_KEY is set in the properties of the
message, then the "topic + ‘#’ + UNIQ_KEY" will be used as the index. Likewise,
if the KEYS is set in the properties of the message (mu [...]
-The index data contains four fields, Key Hash, CommitLog offset, Timestamp and
NextIndex offset, for a total of 20 Bytes. The NextIndex offset of the index
data will point to the previous index data if the Key Hash of the index data is
the same as that of the previous index data. If a hash conflict occurs, then
the NextIndex offset can be used as the field to string all conflicting indexes
in a linked list. What the Timestamp records is the time difference between two
storeTimestamps, in [...]
+The header of IndexFile contains eight fields, `beginTimestamp`(8 bytes),
`endTimestamp`(8 bytes), `beginPhyOffset`(8 bytes), `endPhyOffset`(8 bytes),
`hashSlotCount`(4 bytes), and `indexCount`(4 bytes).`beginTimestamp` and
`endTimestamp` represents the storeTimestamp of the message corresponding to
the first and last index, `beginPhyOffset` and `endPhyOffset` represent the
physical offset of the message corresponding to the first and last index.
`hashSlotCount` represents the count of h [...]
+
+The index data contains four fields, `Key Hash`, `CommitLog offset`,
`Timestamp` and `NextIndex offset`, for a total of 20 Bytes. The `NextIndex
offset` of the index data will point to the previous index data if the `Key
Hash` of the index data is the same as that of the previous index data. If a
hash conflict occurs, then the `NextIndex offset` can be used as the field to
string all conflicting indexes in a linked list. What the `Timestamp` records
is the time difference between the `st [...]
The specific method of "Query Message by Message Key" is that the topic and
message key are used to find the record in the IndexFile, and then read the
message from the file of CommitLog according to the CommitLog offset in this
record.
\ No newline at end of file
