I have been able to define custom time grains (e.g. 15-minute time buckets — cf. #15037), as per the config.py instructions:

# Define how to compute the custom time buckets
TIME_GRAIN_ADDON_EXPRESSIONS = {
    'postgresql': {
        'PT6H': "date_trunc('day', {col}) + date_trunc('hour', {col})::int / 6 * interval '6 h'",
        'PT15M': "date_trunc('hour', {col}) + date_part('minute', {col})::int / 15 * interval '15 min'",
    },
}

# Register these custom time grain
TIME_GRAIN_ADDONS = {
    "PT6H": "6 hours",
    "PT15M": "15 minutes",
}

My custom time grains are then sorted after the default time grains:

Expected results

I would expect all time grains to be sorted by increasing duration. In the example above:

[…]

• minute
• 15 minutes
• hour
• 6 hours
• day

[…]

Actual results

My custom time grains are sorted after any default ones. Their relative order is defined by the by TIME_GRAIN_ADDON_EXPRESSIONS keys' order, and not TIME_GRAIN_ADDONS's ones.

How to reproduce the bug

1. Define custom time grain in superset_config.py, as above,
2. Go to Explore / {any Time Series chart}
3. Click on the Time Grain dropdown menu.

Environment

• superset version: superset 1.1.0

Checklist

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven't found one similar.