# ANALYZE: Interpreting rows and filtered members
This article describes how to interpret `r_rows` and `r_filtered` members in `ANALYZE FORMAT=JSON` when an index-based access method is used.
## Index-based access method
Index-based access method may employ some or all of the following:
* [Index Condition Pushdown](/docs/server/ha-and-performance/optimization-and-tuning/query-optimizations/index-condition-pushdown.md)
* [Rowid Filtering](/docs/server/ha-and-performance/optimization-and-tuning/query-optimizations/rowid-filtering-optimization.md)
* attached\_condition checking
Consider a table access which does all three:
```json
"table": {
"table_name": "t1",
"access_type": "range",
"possible_keys": ...,
"key": "INDEX1",
...
"rowid_filter": {
...
"r_selectivity_pct": n.nnn,
},
...
"rows": 123,
"r_rows": 125,
...
"filtered": 8.476269722,
"r_filtered": 100,
"index_condition": "cond1",
"attached_condition": "cond2"
}
```
The access is performed as follows:
### Access diagram
## Statistics values in MariaDB before 11.5
In MariaDB versions before 11.5, the counters were counted as follows:
that is,
* `r_rows` is counted after Index Condition Pushdown check and Rowid Filter check.
* `r_filtered` only counts selectivity of the `attached_condition`.
* selectivity of the Rowid Filter is in `rowid_filter.r_selectivity_pct`.
## Statistics values in [MariaDB 11.5](/docs/release-notes/community-server/old-releases/11.5/what-is-mariadb-115.md) and later versions
Starting from [MariaDB 11.5](/docs/release-notes/community-server/old-releases/11.5/what-is-mariadb-115.md) ([MDEV-18478](https://jira.mariadb.org/browse/MDEV-18478)), the row counters are:
* `r_index_rows` counts the number of enumerated index tuples, before any checks are made
* `r_rows` is the same as before - number of rows after index checks.
The selectivity counters are:
* `r_icp_filtered` is the percentage of records left after pushed index condition check.
* `rowid_filter.r_selectivity_pct` shows selectivity of Rowid Filter, as before.
* `r_filtered` is the selectivity of `attached_condition` check, as before.
* `r_total_filtered` is the combined selectivity of all checks.
### ANALYZE output members
in ANALYZE FORMAT=JSON output these members are placed as follows:
```json
"table": {
"table_name": ...,
"rows": 426,
"r_index_rows": 349,
"r_rows": 34,
```
Whenever applicable, `r_index_rows` is shown. It is comparable with `rows` - both are numbers of rows to enumerate before any filtering is done.\
If `r_index_rows` is not shown, `r_rows` shows the number of records enumerated.
Then, filtering members:
```json
...
"filtered": 8.476269722,
"r_total_filtered": 9.742120344,
```
`filtered` is comparable with `r_total_filtered`: both show total amount of filtering.
```json
...
"index_condition": "lineitem.l_quantity > 47",
"r_icp_filtered": 100,
```
ICP and its observed filtering. The optimizer doesn't compute an estimate for this currently.
```json
...
"attached_condition": "lineitem.l_shipDATE between '1997-01-01' and '1997-06-30'",
"r_filtered": 100
```
`attached_condition` and its observed filtering.
*This page is licensed: CC BY-SA / Gnu FDL*
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