diff --git a/alter_column_to_nullable/.tinyenv b/alter_column_to_nullable/.tinyenv
new file mode 100644
index 00000000..3281ddfa
--- /dev/null
+++ b/alter_column_to_nullable/.tinyenv
@@ -0,0 +1,31 @@
+
+# VERSION format is major.minor.patch-post where major, minor, patch and post are integer numbers
+# bump post to deploy to the current live Release, rollback to previous post version is not available
+# bump patch or minor to deploy a new Release and auto-promote it to live. Add TB_AUTO_PROMOTE=0 to create the Release in preview status
+# bump major to deploy a new Release in preview status
+VERSION=0.0.0
+
+
+
+##########
+# OPTIONAL env vars
+# Deploy a new Release in preview status (default is 1)
+# TB_AUTO_PROMOTE=0
+
+# Check if deploy requires backfilling on preview (default is 1)
+# TB_CHECK_BACKFILL_REQUIRED=0
+
+# Force old Releases deletion on promote (default is 0)
+# Setting it to 1 will remove oldest rollback Releases even when some resource is still in use
+# TB_FORCE_REMOVE_OLDEST_ROLLBACK=0
+
+# Don't print CLI version warning message if there's a new available version
+# TB_VERSION_WARNING=0
+
+# Skip regression tests
+# TB_SKIP_REGRESSION=0
+
+# Use `OBFUSCATE_REGEX_PATTERN` and `OBFUSCATE_PATTERN_SEPARATOR` environment variables to define a regex pattern and a separator (in case of a single string with multiple regex) to obfuscate secrets in the CLI output.
+# OBFUSCATE_REGEX_PATTERN="https://(www\.)?[^/]+||^Follow these instructions =>"
+# OBFUSCATE_PATTERN_SEPARATOR=||
+##########
diff --git a/alter_column_to_nullable/datasources/analytics_events.datasource b/alter_column_to_nullable/datasources/analytics_events.datasource
new file mode 100644
index 00000000..241f6984
--- /dev/null
+++ b/alter_column_to_nullable/datasources/analytics_events.datasource
@@ -0,0 +1,16 @@
+TOKEN "tracker" APPEND
+
+DESCRIPTION >
+    Analytics events landing data source
+
+SCHEMA >
+    `timestamp` DateTime `json:$.timestamp`,
+    `session_id` String `json:$.session_id`,
+    `action` LowCardinality(String) `json:$.action`,
+    `version` LowCardinality(String) `json:$.version`,
+    `payload` String `json:$.payload`
+
+ENGINE "MergeTree"
+ENGINE_PARTITION_KEY "toYYYYMM(timestamp)"
+ENGINE_SORTING_KEY "timestamp"
+ENGINE_TTL "timestamp + toIntervalDay(60)"
diff --git a/alter_column_to_nullable/datasources/analytics_pages_mv.datasource b/alter_column_to_nullable/datasources/analytics_pages_mv.datasource
new file mode 100644
index 00000000..68a76061
--- /dev/null
+++ b/alter_column_to_nullable/datasources/analytics_pages_mv.datasource
@@ -0,0 +1,13 @@
+
+SCHEMA >
+    `date` Date,
+    `device` String,
+    `browser` String,
+    `location` String,
+    `pathname` String,
+    `visits` AggregateFunction(uniq, String),
+    `hits` AggregateFunction(count)
+
+ENGINE "AggregatingMergeTree"
+ENGINE_PARTITION_KEY "toYYYYMM(date)"
+ENGINE_SORTING_KEY "date, device, browser, location, pathname"
diff --git a/alter_column_to_nullable/datasources/analytics_sessions_mv.datasource b/alter_column_to_nullable/datasources/analytics_sessions_mv.datasource
new file mode 100644
index 00000000..267771df
--- /dev/null
+++ b/alter_column_to_nullable/datasources/analytics_sessions_mv.datasource
@@ -0,0 +1,14 @@
+
+SCHEMA >
+    `date` Date,
+    `session_id` String,
+    `device` SimpleAggregateFunction(any, String),
+    `browser` SimpleAggregateFunction(any, String),
+    `location` SimpleAggregateFunction(any, String),
+    `first_hit` SimpleAggregateFunction(min, DateTime),
+    `latest_hit` SimpleAggregateFunction(max, DateTime),
+    `hits` AggregateFunction(count)
+
+ENGINE "AggregatingMergeTree"
+ENGINE_PARTITION_KEY "toYYYYMM(date)"
+ENGINE_SORTING_KEY "date, session_id"
diff --git a/alter_column_to_nullable/datasources/analytics_sources_mv.datasource b/alter_column_to_nullable/datasources/analytics_sources_mv.datasource
new file mode 100644
index 00000000..7235d468
--- /dev/null
+++ b/alter_column_to_nullable/datasources/analytics_sources_mv.datasource
@@ -0,0 +1,13 @@
+
+SCHEMA >
+    `date` Date,
+    `device` String,
+    `browser` String,
+    `location` String,
+    `referrer` String,
+    `visits` AggregateFunction(uniq, String),
+    `hits` AggregateFunction(count)
+
+ENGINE "AggregatingMergeTree"
+ENGINE_PARTITION_KEY "toYYYYMM(date)"
+ENGINE_SORTING_KEY "date, device, browser, location, referrer"
diff --git a/alter_column_to_nullable/datasources/fixtures/.gitkeep b/alter_column_to_nullable/datasources/fixtures/.gitkeep
new file mode 100644
index 00000000..e69de29b
diff --git a/alter_column_to_nullable/pipes/analytics_hits.pipe b/alter_column_to_nullable/pipes/analytics_hits.pipe
new file mode 100644
index 00000000..05400081
--- /dev/null
+++ b/alter_column_to_nullable/pipes/analytics_hits.pipe
@@ -0,0 +1,65 @@
+DESCRIPTION >
+	Parsed `page_hit` events, implementing `browser` and `device` detection logic.
+
+
+TOKEN "dashboard" READ
+
+NODE parsed_hits
+DESCRIPTION >
+    Parse raw page_hit events
+
+SQL >
+
+    SELECT
+        timestamp,
+        action,
+        version,
+        coalesce(session_id, '0') as session_id,
+        JSONExtractString(payload, 'locale') as locale,
+        JSONExtractString(payload, 'location') as location,
+        JSONExtractString(payload, 'referrer') as referrer,
+        JSONExtractString(payload, 'pathname') as pathname,
+        JSONExtractString(payload, 'href') as href,
+        lower(JSONExtractString(payload, 'user-agent')) as user_agent
+    FROM analytics_events
+    where action = 'page_hit'
+
+
+
+NODE endpoint
+SQL >
+
+    SELECT
+        timestamp,
+        action,
+        version,
+        session_id,
+        location,
+        referrer,
+        pathname,
+        href,
+        case
+            when match(user_agent, 'wget|ahrefsbot|curl|urllib|bitdiscovery|\+https://|googlebot')
+            then 'bot'
+            when match(user_agent, 'android')
+            then 'mobile-android'
+            when match(user_agent, 'ipad|iphone|ipod')
+            then 'mobile-ios'
+            else 'desktop'
+        END as device,
+        case
+            when match(user_agent, 'firefox')
+            then 'firefox'
+            when match(user_agent, 'chrome|crios')
+            then 'chrome'
+            when match(user_agent, 'opera')
+            then 'opera'
+            when match(user_agent, 'msie|trident')
+            then 'ie'
+            when match(user_agent, 'iphone|ipad|safari')
+            then 'safari'
+            else 'Unknown'
+        END as browser
+    FROM parsed_hits
+
+
diff --git a/alter_column_to_nullable/pipes/analytics_pages.pipe b/alter_column_to_nullable/pipes/analytics_pages.pipe
new file mode 100644
index 00000000..7c034886
--- /dev/null
+++ b/alter_column_to_nullable/pipes/analytics_pages.pipe
@@ -0,0 +1,21 @@
+NODE analytics_pages_1
+DESCRIPTION >
+    Aggregate by pathname and calculate session and hits
+
+SQL >
+
+    SELECT
+        toDate(timestamp) AS date,
+        device,
+        browser,
+        location,
+        pathname,
+        uniqState(session_id) AS visits,
+        countState() AS hits
+    FROM analytics_hits
+    GROUP BY date, device, browser, location, pathname
+
+TYPE materialized
+DATASOURCE analytics_pages_mv
+
+
diff --git a/alter_column_to_nullable/pipes/analytics_sessions.pipe b/alter_column_to_nullable/pipes/analytics_sessions.pipe
new file mode 100644
index 00000000..2ad6a3a4
--- /dev/null
+++ b/alter_column_to_nullable/pipes/analytics_sessions.pipe
@@ -0,0 +1,22 @@
+NODE analytics_sessions_1
+DESCRIPTION >
+    Aggregate by session_id and calculate session metrics
+
+SQL >
+
+    SELECT
+        toDate(timestamp) AS date,
+        session_id,
+        anySimpleState(device) AS device,
+        anySimpleState(browser) AS browser,
+        anySimpleState(location) AS location,
+        minSimpleState(timestamp) AS first_hit,
+        maxSimpleState(timestamp) AS latest_hit,
+        countState() AS hits
+    FROM analytics_hits
+    GROUP BY date, session_id
+
+TYPE materialized
+DATASOURCE analytics_sessions_mv
+
+
diff --git a/alter_column_to_nullable/pipes/analytics_sources.pipe b/alter_column_to_nullable/pipes/analytics_sources.pipe
new file mode 100644
index 00000000..9a9acb5e
--- /dev/null
+++ b/alter_column_to_nullable/pipes/analytics_sources.pipe
@@ -0,0 +1,23 @@
+NODE analytics_sources_1
+DESCRIPTION >
+    Aggregate by referral and calculate session and hits
+
+SQL >
+
+    WITH (SELECT domainWithoutWWW(href) FROM analytics_hits LIMIT 1) AS currenct_domain
+    SELECT
+        toDate(timestamp) AS date,
+        device,
+        browser,
+        location,
+        referrer,
+        uniqState(session_id) AS visits,
+        countState() AS hits
+    FROM analytics_hits
+    WHERE domainWithoutWWW(referrer) != currenct_domain
+    GROUP BY date, device, browser, location, referrer
+
+TYPE materialized
+DATASOURCE analytics_sources_mv
+
+
diff --git a/alter_column_to_nullable/pipes/kpis.pipe b/alter_column_to_nullable/pipes/kpis.pipe
new file mode 100644
index 00000000..3dbfb8e8
--- /dev/null
+++ b/alter_column_to_nullable/pipes/kpis.pipe
@@ -0,0 +1,138 @@
+DESCRIPTION >
+	Summary with general KPIs per date, including visits, page views, bounce rate and average session duration.
+    Accepts `date_from` and `date_to` date filter, all historical data if not passed.
+    Daily granularity, except when filtering one single day (hourly)
+
+
+TOKEN "dashboard" READ
+
+NODE timeseries
+DESCRIPTION >
+    Generate a timeseries for the specified time range, so we call fill empty data points.
+            Filters "future" data points.
+
+SQL >
+
+    %
+            {% set _single_day = defined(date_from) and day_diff(date_from, date_to) == 0 %}
+            with
+                {% if defined(date_from) %}
+                    toStartOfDay(
+                        toDate(
+                            {{
+                                Date(
+                                    date_from,
+                                    description="Starting day for filtering a date range",
+                                    required=False,
+                                )
+                            }}
+                        )
+                    ) as start,
+                {% else %} toStartOfDay(timestampAdd(today(), interval -7 day)) as start,
+                {% end %}
+                {% if defined(date_to) %}
+                    toStartOfDay(
+                        toDate(
+                            {{
+                                Date(
+                                    date_to,
+                                    description="Finishing day for filtering a date range",
+                                    required=False,
+                                )
+                            }}
+                        )
+                    ) as end
+                {% else %} toStartOfDay(today()) as end
+                {% end %}
+            {% if _single_day %}
+                select
+                    arrayJoin(
+                        arrayMap(
+                            x -> toDateTime(x),
+                            range(
+                                toUInt32(toDateTime(start)), toUInt32(timestampAdd(end, interval 1 day)), 3600
+                            )
+                        )
+                    ) as date
+            {% else %}
+                select
+                    arrayJoin(
+                        arrayMap(
+                            x -> toDate(x),
+                            range(toUInt32(start), toUInt32(timestampAdd(end, interval 1 day)), 24 * 3600)
+                        )
+                    ) as date
+            {% end %}
+            where date <= now()
+
+
+
+NODE hits
+DESCRIPTION >
+    Group by sessions and calculate metrics at that level
+
+SQL >
+
+    %
+            {% if defined(date_from) and day_diff(date_from, date_to) == 0 %}
+                select
+                    toStartOfHour(timestamp) as date,
+                    session_id,
+                    uniq(session_id) as visits,
+                    count() as pageviews,
+                    case when min(timestamp) = max(timestamp) then 1 else 0 end as is_bounce,
+                    max(timestamp) as latest_hit_aux,
+                    min(timestamp) as first_hit_aux
+                from analytics_hits
+                where toDate(timestamp) = {{ Date(date_from) }}
+                group by toStartOfHour(timestamp), session_id
+            {% else %}
+                select
+                    date,
+                    session_id,
+                    uniq(session_id) as visits,
+                    countMerge(hits) as pageviews,
+                    case when min(first_hit) = max(latest_hit) then 1 else 0 end as is_bounce,
+                    max(latest_hit) as latest_hit_aux,
+                    min(first_hit) as first_hit_aux
+                from analytics_sessions_mv
+                where
+                    {% if defined(date_from) %} date >= {{ Date(date_from) }}
+                    {% else %} date >= timestampAdd(today(), interval -7 day)
+                    {% end %}
+                    {% if defined(date_to) %} and date <= {{ Date(date_to) }}
+                    {% else %} and date <= today()
+                    {% end %}
+                group by date, session_id
+            {% end %}
+
+
+
+NODE data
+DESCRIPTION >
+    General KPIs per date, works for both summary metrics and trends charts.
+
+SQL >
+
+    select
+        date,
+        uniq(session_id) as visits,
+        sum(pageviews) as pageviews,
+        sum(case when latest_hit_aux = first_hit_aux then 1 end) / visits as bounce_rate,
+        avg(latest_hit_aux - first_hit_aux) as avg_session_sec
+    from hits
+    group by date
+
+
+
+NODE endpoint
+DESCRIPTION >
+    Join and generate timeseries with metrics
+
+SQL >
+
+    select a.date, b.visits, b.pageviews, b.bounce_rate, b.avg_session_sec
+    from timeseries a
+    left join data b using date
+
+
diff --git a/alter_column_to_nullable/pipes/top_browsers.pipe b/alter_column_to_nullable/pipes/top_browsers.pipe
new file mode 100644
index 00000000..03c89f0c
--- /dev/null
+++ b/alter_column_to_nullable/pipes/top_browsers.pipe
@@ -0,0 +1,35 @@
+DESCRIPTION >
+	Top Browsers ordered by most visits.
+    Accepts `date_from` and `date_to` date filter. Defaults to last 7 days.
+    Also `skip` and `limit` parameters for pagination.
+
+
+TOKEN "dashboard" READ
+
+NODE endpoint
+DESCRIPTION >
+    Group by browser and calcualte hits and visits
+
+SQL >
+
+    %
+            select browser, uniqMerge(visits) as visits, countMerge(hits) as hits
+            from analytics_sources_mv
+            where
+                {% if defined(date_from) %}
+                    date
+                    >=
+                    {{ Date(date_from, description="Starting day for filtering a date range", required=False) }}
+                {% else %} date >= timestampAdd(today(), interval -7 day)
+                {% end %}
+                {% if defined(date_to) %}
+                    and date
+                    <=
+                    {{ Date(date_to, description="Finishing day for filtering a date range", required=False) }}
+                {% else %} and date <= today()
+                {% end %}
+            group by browser
+            order by visits desc
+            limit {{ Int32(skip, 0) }},{{ Int32(limit, 50) }}
+
+
diff --git a/alter_column_to_nullable/pipes/top_devices.pipe b/alter_column_to_nullable/pipes/top_devices.pipe
new file mode 100644
index 00000000..400623a9
--- /dev/null
+++ b/alter_column_to_nullable/pipes/top_devices.pipe
@@ -0,0 +1,35 @@
+DESCRIPTION >
+	Top Device Types ordered by most visits.
+    Accepts `date_from` and `date_to` date filter. Defaults to last 7 days.
+    Also `skip` and `limit` parameters for pagination.
+
+
+TOKEN "dashboard" READ
+
+NODE endpoint
+DESCRIPTION >
+    Group by device and calcualte hits and visits
+
+SQL >
+
+    %
+            select device, uniqMerge(visits) as visits, countMerge(hits) as hits
+            from analytics_sources_mv
+            where
+                {% if defined(date_from) %}
+                    date
+                    >=
+                    {{ Date(date_from, description="Starting day for filtering a date range", required=False) }}
+                {% else %} date >= timestampAdd(today(), interval -7 day)
+                {% end %}
+                {% if defined(date_to) %}
+                    and date
+                    <=
+                    {{ Date(date_to, description="Finishing day for filtering a date range", required=False) }}
+                {% else %} and date <= today()
+                {% end %}
+            group by device
+            order by visits desc
+            limit {{ Int32(skip, 0) }},{{ Int32(limit, 50) }}
+
+
diff --git a/alter_column_to_nullable/pipes/top_locations.pipe b/alter_column_to_nullable/pipes/top_locations.pipe
new file mode 100644
index 00000000..a433f6c6
--- /dev/null
+++ b/alter_column_to_nullable/pipes/top_locations.pipe
@@ -0,0 +1,35 @@
+DESCRIPTION >
+	Top visting Countries ordered by most visits.
+    Accepts `date_from` and `date_to` date filter. Defaults to last 7 days.
+    Also `skip` and `limit` parameters for pagination.
+
+
+TOKEN "dashboard" READ
+
+NODE endpoint
+DESCRIPTION >
+    Group by pagepath and calcualte hits and visits
+
+SQL >
+
+    %
+            select location, uniqMerge(visits) as visits, countMerge(hits) as hits
+            from analytics_pages_mv
+            where
+                {% if defined(date_from) %}
+                    date
+                    >=
+                    {{ Date(date_from, description="Starting day for filtering a date range", required=False) }}
+                {% else %} date >= timestampAdd(today(), interval -7 day)
+                {% end %}
+                {% if defined(date_to) %}
+                    and date
+                    <=
+                    {{ Date(date_to, description="Finishing day for filtering a date range", required=False) }}
+                {% else %} and date <= today()
+                {% end %}
+            group by location
+            order by visits desc
+            limit {{ Int32(skip, 0) }},{{ Int32(limit, 50) }}
+
+
diff --git a/alter_column_to_nullable/pipes/top_pages.pipe b/alter_column_to_nullable/pipes/top_pages.pipe
new file mode 100644
index 00000000..a8527bf5
--- /dev/null
+++ b/alter_column_to_nullable/pipes/top_pages.pipe
@@ -0,0 +1,35 @@
+DESCRIPTION >
+	Most visited pages for a given period.
+    Accepts `date_from` and `date_to` date filter. Defaults to last 7 days.
+    Also `skip` and `limit` parameters for pagination.
+
+
+TOKEN "dashboard" READ
+
+NODE endpoint
+DESCRIPTION >
+    Group by pagepath and calcualte hits and visits
+
+SQL >
+
+    %
+            select pathname, uniqMerge(visits) as visits, countMerge(hits) as hits
+            from analytics_pages_mv
+            where
+                {% if defined(date_from) %}
+                    date
+                    >=
+                    {{ Date(date_from, description="Starting day for filtering a date range", required=False) }}
+                {% else %} date >= timestampAdd(today(), interval -7 day)
+                {% end %}
+                {% if defined(date_to) %}
+                    and date
+                    <=
+                    {{ Date(date_to, description="Finishing day for filtering a date range", required=False) }}
+                {% else %} and date <= today()
+                {% end %}
+            group by pathname
+            order by visits desc
+            limit {{ Int32(skip, 0) }},{{ Int32(limit, 50) }}
+
+
diff --git a/alter_column_to_nullable/pipes/top_sources.pipe b/alter_column_to_nullable/pipes/top_sources.pipe
new file mode 100644
index 00000000..146b5a98
--- /dev/null
+++ b/alter_column_to_nullable/pipes/top_sources.pipe
@@ -0,0 +1,35 @@
+DESCRIPTION >
+	Top traffic sources (domains), ordered by most visits.
+    Accepts `date_from` and `date_to` date filter. Defaults to last 7 days.
+    Also `skip` and `limit` parameters for pagination.
+
+
+TOKEN "dashboard" READ
+
+NODE endpoint
+DESCRIPTION >
+    Group by referral and calcualte hits and visits.
+
+SQL >
+
+    %
+            select domainWithoutWWW(referrer) as referrer, uniqMerge(visits) as visits, countMerge(hits) as hits
+            from analytics_sources_mv
+            where
+                {% if defined(date_from) %}
+                    date
+                    >=
+                    {{ Date(date_from, description="Starting day for filtering a date range", required=False) }}
+                {% else %} date >= timestampAdd(today(), interval -7 day)
+                {% end %}
+                {% if defined(date_to) %}
+                    and date
+                    <=
+                    {{ Date(date_to, description="Finishing day for filtering a date range", required=False) }}
+                {% else %} and date <= today()
+                {% end %}
+            group by referrer
+            order by visits desc
+            limit {{ Int32(skip, 0) }},{{ Int32(limit, 50) }}
+
+
diff --git a/alter_column_to_nullable/pipes/trend.pipe b/alter_column_to_nullable/pipes/trend.pipe
new file mode 100644
index 00000000..018074f6
--- /dev/null
+++ b/alter_column_to_nullable/pipes/trend.pipe
@@ -0,0 +1,42 @@
+DESCRIPTION >
+	Visits trend over time for the last 30 minutes, filling the blanks.
+    Works great for the realtime chart.
+
+
+TOKEN "dashboard" READ
+
+NODE timeseries
+DESCRIPTION >
+    Generate a timeseries for the last 30 minutes, so we call fill empty data points
+
+SQL >
+
+    with (now() - interval 30 minute) as start
+    select addMinutes(toStartOfMinute(start), number) as t
+    from (select arrayJoin(range(1, 31)) as number)
+
+
+
+NODE hits
+DESCRIPTION >
+    Get last 30 minutes metrics gropued by minute
+
+SQL >
+
+    select toStartOfMinute(timestamp) as t, uniq(session_id) as visits
+    from analytics_hits
+    where timestamp >= (now() - interval 30 minute)
+    group by toStartOfMinute(timestamp)
+    order by toStartOfMinute(timestamp)
+
+
+
+NODE endpoint
+DESCRIPTION >
+    Join and generate timeseries with metrics for the last 30 minutes
+
+SQL >
+
+    select a.t, b.visits from timeseries a left join hits b on a.t = b.t order by a.t
+
+
diff --git a/alter_column_to_nullable/requirements.txt b/alter_column_to_nullable/requirements.txt
new file mode 100644
index 00000000..86035df9
--- /dev/null
+++ b/alter_column_to_nullable/requirements.txt
@@ -0,0 +1 @@
+tinybird-cli>=4,<5
\ No newline at end of file
diff --git a/alter_column_to_nullable/scripts/append_fixtures.sh b/alter_column_to_nullable/scripts/append_fixtures.sh
new file mode 100755
index 00000000..e8745565
--- /dev/null
+++ b/alter_column_to_nullable/scripts/append_fixtures.sh
@@ -0,0 +1,21 @@
+
+#!/usr/bin/env bash
+set -euxo pipefail
+
+directory="datasources/fixtures"
+extensions=("csv" "ndjson")
+
+absolute_directory=$(realpath "$directory")
+
+for extension in "${extensions[@]}"; do
+  file_list=$(find "$absolute_directory" -type f -name "*.$extension")
+
+  for file_path in $file_list; do
+    file_name=$(basename "$file_path")
+    file_name_without_extension="${file_name%.*}"
+
+    command="tb datasource append $file_name_without_extension datasources/fixtures/$file_name"
+    echo $command
+    $command
+  done
+done
diff --git a/alter_column_to_nullable/scripts/exec_test.sh b/alter_column_to_nullable/scripts/exec_test.sh
new file mode 100755
index 00000000..50571d95
--- /dev/null
+++ b/alter_column_to_nullable/scripts/exec_test.sh
@@ -0,0 +1,58 @@
+
+#!/usr/bin/env bash
+set -euxo pipefail
+
+export TB_VERSION_WARNING=0
+
+run_test() {
+    t=$1
+    echo "** Running $t **"
+    echo "** $(cat $t)"
+    tmpfile=$(mktemp)
+    retries=0
+    TOTAL_RETRIES=3
+
+    # When appending fixtures, we need to retry in case of the data is not replicated in time
+    while [ $retries -lt $TOTAL_RETRIES ]; do
+        # Run the test and store the output in a temporary file
+        bash $t $2 >$tmpfile
+        exit_code=$?
+        if [ "$exit_code" -eq 0 ]; then
+            # If the test passed, break the loop
+            if diff -B ${t}.result $tmpfile >/dev/null 2>&1; then
+                break
+            # If the test failed, increment the retries counter and try again
+            else
+                retries=$((retries+1))
+            fi
+        # If the bash command failed, print an error message and break the loop
+        else
+            break
+        fi
+    done
+
+    if diff -B ${t}.result $tmpfile >/dev/null 2>&1; then
+        echo "✅ Test $t passed"
+        rm $tmpfile
+        return 0
+    elif [ $retries -eq $TOTAL_RETRIES ]; then
+        echo "🚨 ERROR: Test $t failed, diff:";
+        diff -B ${t}.result $tmpfile
+        rm $tmpfile
+        return 1
+    else
+        echo "🚨 ERROR: Test $t failed with bash command exit code $?"
+        cat $tmpfile
+        rm $tmpfile
+        return 1
+    fi
+    echo ""
+}
+export -f run_test
+
+fail=0
+find ./tests -name "*.test" -print0 | xargs -0 -I {} -P 4 bash -c 'run_test "$@"' _ {} || fail=1
+
+if [ $fail == 1 ]; then
+  exit -1;
+fi
diff --git a/alter_column_to_nullable/tests/.gitkeep b/alter_column_to_nullable/tests/.gitkeep
new file mode 100644
index 00000000..e69de29b