sivaraman-27 commented on issue #28733:
URL:
https://github.com/apache/shardingsphere/issues/28733#issuecomment-1760737051
Added some info below: (The tables below are just for example representation)
**Tables involved:**
- shard_lookup
- orders
- order_details
- order_ratings
shard_lookup:
| order_id | shard_no |
| ------------- | ------------- |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 2 |
orders: [This table is present in shard_no = 1]
| order_id | user_id | order_amount
| --------- | -------- | ---------------- |
| 1 | 100 | $8 |
| 2 | 101 | $10 |
order_details: [This table is present in shard_no = 1]
| order_id | restaurant_id | ordered_on | delivered_on
| --------- | -------- | ---------------- | ----------------- |
| 1 | 8001 | epoch_time | epoch_time |
| 2 | 8002 | epoch_time | epoch_time |
order_ratings: [This table is present in shard_no = 1]
| order_id | rating_value | rated_on | will_recommed_to_others
| --------- | -------- | ---------------- | ----------------- |
| 1 | 5 | epoch_time | Yes |
| 2 | 4 | epoch_time | Yes |
* The tables above are present in shard_no = 1. Assume these tables with
same name and structure is present in all shards.
* So, for querying any data from 'orders', 'order_details', 'order_ratings',
first correct shard is obtained from 'shard_lookup' using order_id, then
appropriate table is queried.
**Examples:**
1. For getting amount for order_id = 1, below steps are followed
* Query 'shard_lookup' for order_id = 1, which gives shard_1
* Go to shard_1, query 'orders' table for order_id = 1 which will give
'$8'
2. For getting amount for order_id = 4, below steps are followed
* Query 'shard_lookup' for order_id = 4, which gives shard_2
* Go to shard_2, query 'orders' table which will give appropriate amount
* I know I can write custom logic, but just wanted to know if apache
shardingsphere/proxy will be helpful because you guys would have solved lots of
common problems.
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