docs: update benchmarks (#155)

* docs: update benchmarks

* docs: update benchmark results

Co-authored-by: larkee <larkee@users.noreply.github.com>
Co-authored-by: skuruppu <skuruppu@google.com>

BENCHMARKS.md

@@ -8,17 +8,19 @@ The test suite requirements:
 
 Use `PROJECT`, `INSTANCE` and `DATABASE` module constants to set a project to execute tests on.
 
-# 07-11-2021
+The following measurements were made on a VM instance.
+
+# 25-11-2021
 
 |Test|mean, sec|error|std_dev|
 |----|-------|-----|--------|
-|SPANNER insert_one_row_with_fetch_after| 0.91|0.01|0.09|
-|ALCHEMY insert_one_row_with_fetch_after|  1.07| 0.0|0.03|
-|SPANNER read_one_row| 0.33| 0.0| 0.01|
-|ALCHEMY read_one_row| 0.3| 0.0| 0.01|
-|SPANNER insert_many_rows|  1.37| 0.02| 0.12|
-|ALCHEMY insert_many_rows|  24.41| 0.07| 0.49|
-|SPANNER select_many_rows| 0.31| 0.02| 0.08|
-|ALCHEMY select_many_rows|   0.22| 0.03| 0.01|
-|SPANNER insert_many_rows_with_mutations| 0.34| 0.0| 0.03|
-|SQLALCHEMY insert_many_rows_with_mutations| 25.1| 0.03| 0.31|
+|SPANNER insert_one_row_with_fetch_after| 0.16|0.0|0.03|
+|ALCHEMY insert_one_row_with_fetch_after|  0.11| 0.0|0.02|
+|SPANNER read_one_row| 0.04| 0.0| 0.01|
+|ALCHEMY read_one_row| 0.01| 0.0| 0.0|
+|SPANNER insert_many_rows|  0.33| 0.01| 0.05|
+|ALCHEMY insert_many_rows|  0.32| 0.01| 0.06|
+|SPANNER select_many_rows| 0.04| 0.0| 0.01|
+|ALCHEMY select_many_rows|   0.03| 0.0| 0.0|
+|SPANNER insert_many_rows_with_mutations| 0.07| 0.0| 0.03|
+|SQLALCHEMY insert_many_rows_with_mutations| 0.31| 0.01| 0.07|