# Objective
- since #9685 ,bevy introduce automatic batching of draw commands,
- `batch_and_prepare_render_phase` take the responsibility for batching
`phaseItem`,
- `GetBatchData` trait is used for indentify each phaseitem how to
batch. it defines a associated type `Data `used for Query to fetch data
from world.
- however,the impl of `GetBatchData ` in bevy always set ` type
Data=Entity` then we acually get following code
`let entity:Entity =query.get(item.entity())` that cause unnecessary
overhead .
## Solution
- remove associated type `Data ` and `Filter` from `GetBatchData `,
- change the type of the `query_item ` parameter in get_batch_data from`
Self::Data` to `Entity`.
- `batch_and_prepare_render_phase ` no longer takes a query using
`F::Data, F::Filter`
- `get_batch_data `now returns `Option<(Self::BufferData,
Option<Self::CompareData>)>`
---
## Performance
based in main merged with #11290
Window 11 ,Intel 13400kf, NV 4070Ti
frame time from 3.34ms to 3 ms, ~ 10%
`batch_and_prepare_render_phase` from 800us ~ 400 us
## Migration Guide
trait `GetBatchData` no longer hold associated type `Data `and `Filter`
`get_batch_data` `query_item `type from `Self::Data` to `Entity` and
return `Option<(Self::BufferData, Option<Self::CompareData>)>`
`batch_and_prepare_render_phase` should not have a query
04aedf12fa