> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-parallel-read-in-order-multi-part.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# azure_* session settings

> ClickHouse session settings in the azure_* generated group.

export const VersionHistory = ({rows = []}) => {
  if (rows.length === 0) {
    return null;
  }
  const headers = ["Version", "Default value", "Comment"];
  const border = "1px solid rgba(128, 128, 128, 0.3)";
  const cell = {
    border,
    padding: "0.25rem 0.5rem",
    textAlign: "start",
    verticalAlign: "top"
  };
  return <details className="not-prose" style={{
    border,
    borderRadius: "0.5rem",
    margin: "0.5rem 0",
    padding: "0.5rem 0.75rem",
    fontSize: "0.8125rem",
    lineHeight: "1.125rem"
  }}>
      <summary style={{
    cursor: "pointer",
    fontWeight: 600,
    opacity: 0.72
  }}>
        Version history
      </summary>
      <table style={{
    borderCollapse: "collapse",
    width: "100%",
    margin: "0.5rem 0 0"
  }}>
        <thead>
          <tr>
            {headers.map(header => <th key={header} style={{
    ...cell,
    fontWeight: 600,
    opacity: 0.72
  }}>
                {header}
              </th>)}
          </tr>
        </thead>
        <tbody>
          {rows.map((row, row_index) => <tr key={row.id ?? row_index}>
              {(row.items ?? []).map((item, item_index) => <td key={item_index} style={{
    ...cell,
    overflowWrap: "anywhere"
  }}>
                  {item?.label}
                </td>)}
            </tr>)}
        </tbody>
      </table>
    </details>;
};

export const SettingsInfoBlock = ({type, default_value, changeable_without_restart}) => {
  return <div className="not-prose" style={{
    display: "flex",
    flexWrap: "wrap",
    alignItems: "baseline",
    columnGap: "0.5rem",
    rowGap: "0.125rem",
    margin: "0.375rem 0",
    fontSize: "0.8125rem",
    lineHeight: "1.125rem"
  }}>
      <div style={{
    fontWeight: 600,
    opacity: 0.72
  }}>Type</div>
      <div style={{
    overflowWrap: "anywhere"
  }}>{type}</div>
      <div style={{
    fontWeight: 600,
    opacity: 0.72,
    marginInlineStart: "0.5rem"
  }}>Default</div>
      <div style={{
    overflowWrap: "anywhere"
  }}>{default_value}</div>
      {changeable_without_restart && <div style={{
    fontWeight: 600,
    opacity: 0.72,
    marginInlineStart: "0.5rem"
  }}>
          Changeable without restart
        </div>}
      {changeable_without_restart && <div style={{
    overflowWrap: "anywhere"
  }}>
          {changeable_without_restart}
        </div>}
    </div>;
};

These settings are available in [system.settings](/reference/system-tables/settings) and are autogenerated from [source](https://github.com/ClickHouse/ClickHouse/blob/master/src/Core/Settings.cpp).

<h2 id="azure_allow_parallel_part_upload">
  azure\_allow\_parallel\_part\_upload
</h2>

<SettingsInfoBlock type="Bool" default_value="1" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.4"},{"label": "true"},{"label": "Use multiple threads for azure multipart upload."}]}]} />

Use multiple threads for azure multipart upload.

<h2 id="azure_check_objects_after_upload">
  azure\_check\_objects\_after\_upload
</h2>

<SettingsInfoBlock type="Bool" default_value="0" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.11"},{"label": "0"},{"label": "Check each uploaded object in azure blob storage to be sure that upload was successful"}]}, {"id": "row-2","items": [{"label": "24.10"},{"label": "0"},{"label": "Check each uploaded object in azure blob storage to be sure that upload was successful"}]}]} />

Check each uploaded object in azure blob storage to be sure that upload was successful

<h2 id="azure_connect_timeout_ms">
  azure\_connect\_timeout\_ms
</h2>

<SettingsInfoBlock type="UInt64" default_value="1000" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "25.8"},{"label": "1000"},{"label": "New setting"}]}]} />

Connection timeout for host from azure disks.

<h2 id="azure_create_new_file_on_insert">
  azure\_create\_new\_file\_on\_insert
</h2>

<SettingsInfoBlock type="Bool" default_value="0" />

Enables or disables creating a new file on each insert in azure engine tables

<h2 id="azure_ignore_file_doesnt_exist">
  azure\_ignore\_file\_doesnt\_exist
</h2>

<SettingsInfoBlock type="Bool" default_value="0" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.6"},{"label": "0"},{"label": "Allow to return 0 rows when the requested files don't exist instead of throwing an exception in AzureBlobStorage table engine"}]}]} />

Ignore absence of file if it does not exist when reading certain keys.

Possible values:

* 1 — `SELECT` returns empty result.
* 0 — `SELECT` throws an exception.

<h2 id="azure_list_object_keys_size">
  azure\_list\_object\_keys\_size
</h2>

<SettingsInfoBlock type="UInt64" default_value="1000" />

Maximum number of files that could be returned in batch by ListObject request

<h2 id="azure_min_upload_part_size">
  azure\_min\_upload\_part\_size
</h2>

<SettingsInfoBlock type="UInt64" default_value="16777216" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.3"},{"label": "16777216"},{"label": "The minimum size of part to upload during multipart upload to Azure blob storage."}]}]} />

The minimum size of part to upload during multipart upload to Azure blob storage.

<h2 id="azure_request_timeout_ms">
  azure\_request\_timeout\_ms
</h2>

<SettingsInfoBlock type="UInt64" default_value="30000" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "25.8"},{"label": "30000"},{"label": "New setting"}]}]} />

Idleness timeout for sending and receiving data to/from azure. Fail if a single TCP read or write call blocks for this long.

<h2 id="azure_skip_empty_files">
  azure\_skip\_empty\_files
</h2>

<SettingsInfoBlock type="Bool" default_value="0" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.6"},{"label": "0"},{"label": "Allow to skip empty files in azure table engine"}]}]} />

Enables or disables skipping empty files in S3 engine.

Possible values:

* 0 — `SELECT` throws an exception if empty file is not compatible with requested format.
* 1 — `SELECT` returns empty result for empty file.

<h2 id="azure_strict_upload_part_size">
  azure\_strict\_upload\_part\_size
</h2>

<SettingsInfoBlock type="UInt64" default_value="0" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.3"},{"label": "0"},{"label": "The exact size of part to upload during multipart upload to Azure blob storage."}]}]} />

The exact size of part to upload during multipart upload to Azure blob storage.

<h2 id="azure_throw_on_zero_files_match">
  azure\_throw\_on\_zero\_files\_match
</h2>

<SettingsInfoBlock type="Bool" default_value="0" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.6"},{"label": "0"},{"label": "Allow to throw an error when ListObjects request cannot match any files in AzureBlobStorage engine instead of empty query result"}]}]} />

Throw an error if matched zero files according to glob expansion rules.

Possible values:

* 1 — `SELECT` throws an exception.
* 0 — `SELECT` returns empty result.

<h2 id="azure_truncate_on_insert">
  azure\_truncate\_on\_insert
</h2>

<SettingsInfoBlock type="Bool" default_value="0" />

Enables or disables truncate before insert in azure engine tables.

<h2 id="azure_use_adaptive_timeouts">
  azure\_use\_adaptive\_timeouts
</h2>

<SettingsInfoBlock type="Bool" default_value="1" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "25.8"},{"label": "1"},{"label": "New setting"}]}]} />

When set to `true` than for all azure requests first two attempts are made with low send and receive timeouts.
When set to `false` than all attempts are made with identical timeouts.

<h2 id="azure_validate_etag_on_read">
  azure\_validate\_etag\_on\_read
</h2>

<SettingsInfoBlock type="Bool" default_value="1" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.10"},{"label": "1"},{"label": "New setting to detect concurrent in-place overwrites of Azure blobs during a read by pinning every `GET` to the listed `ETag` with `If-Match` and validating the `ETag` of the response, like `s3_validate_etag_on_read` does for S3. `compatibility` with versions before 26.10 restores the previous behavior (no validation)."}]}]} />

When reading a blob from Azure Blob Storage through the `azureBlobStorage` / `azureBlobStorageCluster` table functions or the `AzureBlobStorage` table engine, pin every `GET` request to the generation of the blob that was observed when it was listed by sending its `ETag` in `If-Match`, and check the `ETag` of the response. A single file read issues many ranged `GET` requests; if the blob is overwritten in place between them (for example by an external writer rewriting a fixed key), the reads can otherwise be stitched together from two different generations of the blob and surface as a corrupted checksum or parse error. The size recorded at listing time is also used as the right bound of the read, so it is only correct for the generation it was recorded for. When a mismatch is detected the read fails with `AZURE_OBJECT_CHANGED_DURING_READ` instead of returning inconsistent data. Disable only for workloads that intentionally read blobs that are being overwritten and can tolerate inconsistent reads.