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merge consecutive reads in shards #1358

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merge consecutive reads in shards #1358

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0a5e9d1
merge consecutive reads in shards
jstriebel Feb 27, 2023
a98c7b8
rm unused line
jstriebel Feb 27, 2023
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44 changes: 43 additions & 1 deletion zarr/_storage/v3_storage_transformers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -340,13 +340,55 @@ def get_partial_values(self, key_ranges):
)
else: # pragma: no cover
transformed_key_ranges.append((key, range_))
values = self.inner_store.get_partial_values(transformed_key_ranges)
merged_key_ranges, reverse_lookup = self._merge_ranges(transformed_key_ranges)
merged_values = self.inner_store.get_partial_values(merged_key_ranges)
values = [merged_values[i][slice_] for i, slice_ in reverse_lookup]
for i in none_indices:
values.insert(i, None)
return values
else:
return StoreV3.get_partial_values(self, key_ranges)

def _merge_ranges(self, key_ranges):
merged_key_ranges = []
reverse_lookup = []
mergable_ranges_per_key = {}
for i, (key, _range) in enumerate(key_ranges):
if self._is_data_key(key):
ranges = mergable_ranges_per_key.setdefault(key, [])
ranges.append((i, _range))
reverse_lookup.append(None) # placeholder
else:
reverse_lookup.append((len(merged_key_ranges), slice(0, None)))
merged_key_ranges.append((key, _range))
for key, indexed_ranges in mergable_ranges_per_key.items():
current_start, current_length = (None, None)
for i, (range_start, range_length) in sorted(indexed_ranges, key=lambda x: x[1]):
# range_start and range_length are positive integers
if current_start is None:
current_start = range_start
current_length = range_length
if range_start > current_start + current_length:
# merging not possible, write out previous range and reset:
merged_key_ranges.append((key, (current_start, current_length)))
current_start = range_start
current_length = range_length
else:
# merge with previous ranges
current_length = max(
current_length,
range_start + range_length - current_start
)
relative_start = range_start - current_start
relative_end = relative_start + range_length
reverse_lookup[i] = (
len(merged_key_ranges),
slice(relative_start, relative_end)
)
# write out last range
merged_key_ranges.append((key, (current_start, current_length)))
return merged_key_ranges, reverse_lookup

def supports_efficient_set_partial_values(self):
return False

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