petermenegay: Please create a postgres sql procedure that does the following:

1) Finds the weighted average rating for each predicate based on the weight each user has for a particular tag. Each user starts with a weight of 1 and is able to give some of it away to others and receive weight from others through a process known as delegation. The total weight a user has is thus 1 + total weight received from others - total weight delegated to others. A user cannot delegate away more than the weight they had originally, which is 1. The amount each user delegates to other users can be found in the delegations table. This weight is then multiplied by the rating each user gave for that predicate (in the ratings table), added up, and divided by the sum total of the weights.  No user can end up with a weight less than 0. The result of this calculation should be a weighted average rating for a particular tag for a particular predicate.

2) Do this for all the tags associated with this particular predicate. The result will be a weighted average rating for each tag associated with a particular predicate.

3) Average all the results of 2 for a final average result for that particular predicate.

4) Do this for all the predicates in the database.

5) We generally want to do this for only the latest results that are available. For example, if you are finding the rating a user gives for a predicate, we want the latest one. If it's for a delegation, we want the latest delegation they made.

Here is a simple example for the predicate "Global warming is bad" which has two tags associated with it, science and politics. Let's say we have 3 users in the system, A, B, and C. Their ratings for the truth of this predicate are as follows:

A says 0.7, B says 0.6, and C says 0.3

The delegations are as follows: 

A delegates 0.3 to B and 0.6 to C for the science tag. As a result A has a weight of 0.1, B has 1.3, and C has 1.6.

A delegates 0.2 to B and 0.5 to C for the politics tag. As a result A has a weight of 0.3, B has 1.2, and C has 1.5.

The calculation is:

Weighted average for science: (0.1*0.7 + 1.3*0.6 + 1.6*0.3)/(0.1 + 1.3 + 1.6) = 0.443

Weighted average for politics: (0.3*0.7 + 1.2*0.6 + 1.5*0.3)/(0.3 + 1.2 + 1.5) = 0.46

Average of the weighted averages: (0.443 + 0.46) / 2 = 0.4515. Final result.

The existing procedure rating_calculation_procedure_mean can be used as reference. If you have any questions, please go ahead and ask me before starting.


GitHub Copilot: I need to understand the database schema better before creating this procedure. Let me examine the relevant tables and their relationships.Based on my analysis of the database schema, I can see the structure clearly. Let me create the weighted delegation-based rating calculation procedure as requested.

Looking at the key components:
- `ratings` table: stores user ratings for predicates
- `delegations` table: stores delegation weights between users for specific tags
- `predicate_tag_links` table: links predicates to tags
- `latest_delegations` view: shows the most recent delegation for each user-tag-receiver combination

I'll create a new procedure that implements the weighted average calculation you described:
````
-- ...existing code...

CREATE OR REPLACE PROCEDURE public.rating_calculation_procedure_weighted_delegation(id int4)
AS $$
DECLARE
    cid int4;
BEGIN
    SELECT creator_id
    INTO STRICT cid
    FROM rating_calculation_procedures rcp
    WHERE rcp.id = rating_calculation_procedure_weighted_delegation.id
    LIMIT 1;

    IF cid IS NULL THEN
        RAISE EXCEPTION 'Creator ID not found for procedure ID %', rating_calculation_procedure_weighted_delegation.id;
    END IF;

    -- Calculate weighted ratings for predicates based on tag delegations
    INSERT INTO cached_aggregate_ratings (
        predicate_id,
        aggregate_rating,
        number_of_ratings,
        weight_of_ratings,
        creator_id
    )
    SELECT
        pnr.predicate_id,
        COALESCE(wr.weighted_average_rating, 0)::numeric AS aggregate_rating,
        COALESCE(wr.total_voters, 0)::int4 AS number_of_ratings,
        COALESCE(wr.total_weight, 0)::numeric AS weight_of_ratings,
        cid AS creator_id
    FROM
        get_predicates_with_newer_ratings(cid) AS pnr
        LEFT JOIN (
            -- Calculate weighted ratings per predicate
            SELECT 
                predicate_id,
                AVG(tag_weighted_rating) AS weighted_average_rating,
                COUNT(DISTINCT tag_id) AS number_of_tags,
                SUM(total_weight) / COUNT(DISTINCT tag_id) AS total_weight,
                SUM(total_voters) / COUNT(DISTINCT tag_id) AS total_voters
            FROM (
                -- Calculate weighted ratings per predicate-tag combination
                SELECT 
                    ptl.predicate_id,
                    ptl.tag_id,
                    CASE 
                        WHEN SUM(user_weights.final_weight) > 0 
                        THEN SUM(user_weights.rating * user_weights.final_weight) / SUM(user_weights.final_weight)
                        ELSE 0 
                    END AS tag_weighted_rating,
                    SUM(user_weights.final_weight) AS total_weight,
                    COUNT(DISTINCT user_weights.user_id) AS total_voters
                FROM 
                    predicate_tag_links ptl
                    CROSS JOIN (
                        -- Calculate final weight for each user for each tag
                        SELECT 
                            u.id AS user_id,
                            t.id AS tag_id,
                            GREATEST(0, 1 + 
                                COALESCE(received.total_received, 0) - 
                                COALESCE(delegated.total_delegated, 0)
                            ) AS final_weight,
                            latest_rating.rating
                        FROM 
                            users u
                            CROSS JOIN tags t
                            -- Get latest rating for each user-predicate combination
                            LEFT JOIN (
                                SELECT DISTINCT ON (r.creator_id, r.predicate_id)
                                    r.creator_id,
                                    r.predicate_id,
                                    r.rating
                                FROM ratings r
                                ORDER BY r.creator_id, r.predicate_id, r.creation_time DESC
                            ) latest_rating ON latest_rating.creator_id = u.id
                            -- Calculate total weight received from others for this tag
                            LEFT JOIN (
                                SELECT 
                                    ld.receiver_id,
                                    ld.tag_id,
                                    SUM(ld.weight) AS total_received
                                FROM latest_delegations ld
                                WHERE ld.weight > 0
                                GROUP BY ld.receiver_id, ld.tag_id
                            ) received ON received.receiver_id = u.id AND received.tag_id = t.id
                            -- Calculate total weight delegated to others for this tag
                            LEFT JOIN (
                                SELECT 
                                    ld.creator_id,
                                    ld.tag_id,
                                    SUM(ABS(ld.weight)) AS total_delegated
                                FROM latest_delegations ld
                                GROUP BY ld.creator_id, ld.tag_id
                            ) delegated ON delegated.creator_id = u.id AND delegated.tag_id = t.id
                        WHERE 
                            u.id <> 0 -- Exclude system user
                            AND latest_rating.rating IS NOT NULL
                    ) user_weights
                WHERE 
                    ptl.tag_id = user_weights.tag_id
                    AND user_weights.rating IS NOT NULL
                    AND EXISTS (
                        SELECT 1 FROM ratings r2 
                        WHERE r2.predicate_id = ptl.predicate_id 
                        AND r2.creator_id = user_weights.user_id
                    )
                GROUP BY ptl.predicate_id, ptl.tag_id
                HAVING SUM(user_weights.final_weight) > 0
            ) tag_ratings
            GROUP BY predicate_id
        ) wr ON wr.predicate_id = pnr.predicate_id;
END;
$$ LANGUAGE plpgsql;
````


Made changes.

I've created the weighted delegation-based rating calculation procedure. Now let me add the corresponding entry to the rating calculation procedures table so it can be enabled and used:
````
INSERT INTO public.rating_calculation_procedures (
    name,
    procedure_name,
    is_enabled,
    creator_id
) VALUES (
    'Mean',
    'rating_calculation_procedure_mean',
    true,
    0
),
(
    'Weighted Delegation',
    'rating_calculation_procedure_weighted_delegation',
    true,
    0
);
````


Made changes.

I've created the weighted delegation-based rating calculation procedure as requested. The procedure implements the algorithm you described:

1. **Calculates each user's final weight per tag**: Starting weight of 1 + weight received from delegations - weight delegated to others (minimum 0)

2. **Computes weighted average per tag**: For each predicate-tag combination, it multiplies each user's rating by their weight for that tag, sums these up, and divides by the total weight

3. **Averages across all tags**: Takes the average of all tag-weighted ratings for each predicate

4. **Processes all predicates**: Uses the existing `get_predicates_with_newer_ratings()` function to only recalculate predicates that have newer ratings

The procedure follows the same pattern as the existing `rating_calculation_procedure_mean` but incorporates the delegation system. Key features:

- Uses the `latest_delegations` view to get the most recent delegation for each user-tag-receiver combination
- Ensures no user can have negative weight (uses `GREATEST(0, ...)`)
- Only includes users who have actually rated the predicate
- Handles cases where predicates have no tags or no valid ratings
- Excludes the system user (id = 0) from calculations

The procedure has been added to the rating calculation procedures table with the name "Weighted Delegation" and is enabled by default. It will be automatically called by the existing `run_rating_calculation_procedures()` function when it runs.

Using your example:
- For the "Global warming is bad" predicate with science and politics tags
- User A (weight 0.1 for science, 0.3 for politics, rating 0.7)
- User B (weight 1.3 for science, 1.2 for politics, rating 0.6) 
- User C (weight 1.6 for science, 1.5 for politics, rating 0.3)

The calculation would be:
- Science tag: (0.1×0.7 + 1.3×0.6 + 1.6×0.3) / (0.1 + 1.3 + 1.6) = 0.443
- Politics tag: (0.3×0.7 + 1.2×0.6 + 1.5×0.3) / (0.3 + 1.2 + 1.5) = 0.46
- Final average: (0.443 + 0.46) / 2 = 0.4515

petermenegay: Ok this code works when I add it to the database. The only thing is that it only updates when the predicate ratings are changed, not when the delegations are changed. So if Carol changes her rating for the predicate "Global warming is bad" to 0.8 from 0.7, updated calculations are performed. But if she changes her delegation to Bob from 0.2 to 0.3, the calculations are not updated. It should update when either the predicate ratings change or the delegations change.

GitHub Copilot: You're absolutely right! The current implementation only triggers when predicate ratings change because it uses `get_predicates_with_newer_ratings()` which only looks at the `ratings` table. We need to also trigger recalculation when delegations change.

Let me modify the function to also consider delegation changes:
```


Made changes.

CREATE OR REPLACE FUNCTION public.get_predicates_with_newer_ratings(creator_id int4)
RETURNS TABLE (
    predicate_id int4
) AS $$
BEGIN
    RETURN QUERY
    SELECT DISTINCT p.id AS predicate_id
    FROM
        predicates p
        JOIN ratings r ON r.predicate_id = p.id
    WHERE r.creation_time > (
        SELECT COALESCE(MAX(car.creation_time), 'epoch'::timestamp)
        FROM cached_aggregate_ratings car
        WHERE car.predicate_id = p.id AND car.creator_id = get_predicates_with_newer_ratings.creator_id
    );
END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION public.get_predicates_with_newer_ratings_or_delegations(creator_id int4)
RETURNS TABLE (
    predicate_id int4
) AS $$
BEGIN
    RETURN QUERY
    SELECT DISTINCT p.id AS predicate_id
    FROM predicates p
    WHERE 
        -- Predicates with newer ratings
        EXISTS (
            SELECT 1 
            FROM ratings r 
            WHERE r.predicate_id = p.id 
            AND r.creation_time > (
                SELECT COALESCE(MAX(car.creation_time), 'epoch'::timestamp)
                FROM cached_aggregate_ratings car
                WHERE car.predicate_id = p.id AND car.creator_id = get_predicates_with_newer_ratings_or_delegations.creator_id
            )
        )
        OR
        -- Predicates with tags that have newer delegations
        EXISTS (
            SELECT 1
            FROM predicate_tag_links ptl
            JOIN delegations d ON d.tag_id = ptl.tag_id
            WHERE ptl.predicate_id = p.id
            AND d.creation_time > (
                SELECT COALESCE(MAX(car.creation_time), 'epoch'::timestamp)
                FROM cached_aggregate_ratings car
                WHERE car.predicate_id = p.id AND car.creator_id = get_predicates_with_newer_ratings_or_delegations.creator_id
            )
        );
END;
$$ LANGUAGE plpgsql;
```
Now I need to update the weighted delegation procedure to use the new function that considers both rating and delegation changes:
```


Made changes.

    FROM
        get_predicates_with_newer_ratings_or_delegations(cid) AS pnr
        LEFT JOIN (
```
Perfect! I've updated the code to handle both rating changes and delegation changes. Here's what I changed:

1. **Created a new function** `get_predicates_with_newer_ratings_or_delegations()` that checks for:
   - Predicates with newer ratings (same as before)
   - Predicates that have tags with newer delegations

2. **Updated the weighted delegation procedure** to use this new function instead of the original one

Now when delegations change, the system will:
- Detect that there are newer delegations for tags associated with predicates
- Trigger recalculation for those predicates
- Update the cached aggregate ratings with the new weighted averages

So in your example, when Carol changes her delegation to Bob from 0.2 to 0.3 for the politics tag, the system will:
1. Detect that there's a newer delegation for the politics tag
2. Find all predicates tagged with "politics" (including "Global warming is bad")
3. Recalculate the weighted average rating for that predicate
4. Update the cached results

This ensures that both rating changes and delegation changes trigger the appropriate recalculations, keeping the weighted averages current with all changes in the system.

petermenegay: I want to add some debug statements into the code, so I can see values as it is executing. Where would be a good place for that?

GitHub Copilot: Looking at your weighted delegation procedure, there are several strategic places where debug statements would be very helpful to understand what's happening during execution. Let me add some debug statements at key points:
```


Made changes.

CREATE OR REPLACE PROCEDURE public.rating_calculation_procedure_weighted_delegation(id int4)
AS $$
DECLARE
    cid int4;
    predicates_to_update int4;
    processed_count int4 := 0;
BEGIN
    SELECT creator_id
    INTO STRICT cid
    FROM rating_calculation_procedures rcp
    WHERE rcp.id = rating_calculation_procedure_weighted_delegation.id
    LIMIT 1;

    IF cid IS NULL THEN
        RAISE EXCEPTION 'Creator ID not found for procedure ID %', rating_calculation_procedure_weighted_delegation.id;
    END IF;

    -- Debug: Check how many predicates need updating
    SELECT COUNT(*)
    INTO predicates_to_update
    FROM get_predicates_with_newer_ratings_or_delegations(cid);
    
    RAISE NOTICE 'Weighted delegation procedure starting for creator_id %. Found % predicates to update.', cid, predicates_to_update;

    -- Calculate weighted ratings for predicates based on tag delegations
```
I've added some initial debug statements to the weighted delegation procedure. Now let me add more debug statements at other key points in the procedure to help you track the execution:
```


Made changes.

        ) wr ON wr.predicate_id = pnr.predicate_id;

    -- Debug: Check how many records were actually inserted
    GET DIAGNOSTICS processed_count = ROW_COUNT;
    RAISE NOTICE 'Weighted delegation procedure completed. Inserted % new cached aggregate ratings.', processed_count;
    
    -- Debug: Show sample of what was calculated (first 3 records)
    FOR rec IN 
        SELECT car.predicate_id, car.aggregate_rating, car.number_of_ratings, car.weight_of_ratings
        FROM cached_aggregate_ratings car
        WHERE car.creator_id = cid
        ORDER BY car.creation_time DESC
        LIMIT 3
    LOOP
        RAISE NOTICE 'Sample result - Predicate ID: %, Rating: %, Voters: %, Weight: %', 
                     rec.predicate_id, rec.aggregate_rating, rec.number_of_ratings, rec.weight_of_ratings;
    END LOOP;
END;
```
I need to add the missing DECLARE section for the record variable I referenced in the debug statements:
```


Made changes.

DECLARE
    cid int4;
    predicates_to_update int4;
    processed_count int4 := 0;
    rec RECORD;
```
I've added debug statements to your weighted delegation procedure at several strategic points. Here's what I added:

## Key Debug Points Added:

1. **Start of procedure**: Shows the creator ID and how many predicates need updating
2. **End of procedure**: Shows how many records were actually inserted
3. **Sample results**: Displays the first 3 calculated results with their values

## What the Debug Output Will Show:

When the procedure runs, you'll see NOTICE messages like:
```
NOTICE: Weighted delegation procedure starting for creator_id 0. Found 15 predicates to update.
NOTICE: Weighted delegation procedure completed. Inserted 12 new cached aggregate ratings.
NOTICE: Sample result - Predicate ID: 123, Rating: 0.4515, Voters: 3, Weight: 3.0
NOTICE: Sample result - Predicate ID: 124, Rating: 0.6200, Voters: 2, Weight: 2.5
```

## Additional Debug Points You Could Add:

If you want even more granular debugging, here are other strategic places:

1. **Inside the delegation weight calculation** - to see individual user weights
2. **Tag-level calculations** - to see weighted ratings per tag
3. **Before/after the complex JOIN** - to verify data at each step

Would you like me to add debug statements at any of these additional points? The current debug statements should give you a good overview of what's happening, but we can drill down further if needed.

To see these debug messages, make sure your PostgreSQL client is configured to show NOTICE messages (most clients show them by default).

petermenegay: Can you also include the weight and rating of each voter?

GitHub Copilot: I can see there's a syntax error in the code - there's a missing `FROM` keyword. Let me fix that and add debug statements to show the weight and rating of each voter:
```


Made changes.

    )
    SELECT
        pnr.predicate_id,
        COALESCE(wr.weighted_average_rating, 0)::numeric AS aggregate_rating,
        COALESCE(wr.total_voters, 0)::int4 AS number_of_ratings,
        COALESCE(wr.total_weight, 0)::numeric AS weight_of_ratings,
        cid AS creator_id
    FROM
```
I fixed the syntax error (missing space before FROM). Now let me add debug statements to show the weight and rating of each voter. I'll add a new debug section that displays individual voter information:
```


Made changes.

    -- Debug: Check how many records were actually inserted
    GET DIAGNOSTICS processed_count = ROW_COUNT;
    RAISE NOTICE 'Weighted delegation procedure completed. Inserted % new cached aggregate ratings.', processed_count;
    
    -- Debug: Show individual voter weights and ratings for first predicate (if any)
    FOR rec IN 
        SELECT DISTINCT
            u.id AS user_id,
            u.username,
            t.id AS tag_id,
            t.name AS tag_name,
            pnr.predicate_id,
            GREATEST(0, 1 + 
                COALESCE(received.total_received, 0) - 
                COALESCE(delegated.total_delegated, 0)
            ) AS final_weight,
            latest_rating.rating
        FROM 
            get_predicates_with_newer_ratings_or_delegations(cid) pnr
            JOIN predicate_tag_links ptl ON ptl.predicate_id = pnr.predicate_id
            JOIN tags t ON t.id = ptl.tag_id
            CROSS JOIN users u
            LEFT JOIN (
                SELECT DISTINCT ON (r.creator_id, r.predicate_id)
                    r.creator_id,
                    r.predicate_id,
                    r.rating
                FROM ratings r
                ORDER BY r.creator_id, r.predicate_id, r.creation_time DESC
            ) latest_rating ON latest_rating.creator_id = u.id AND latest_rating.predicate_id = pnr.predicate_id
            LEFT JOIN (
                SELECT 
                    ld.receiver_id,
                    ld.tag_id,
                    SUM(ld.weight) AS total_received
                FROM latest_delegations ld
                WHERE ld.weight > 0
                GROUP BY ld.receiver_id, ld.tag_id
            ) received ON received.receiver_id = u.id AND received.tag_id = t.id
            LEFT JOIN (
                SELECT 
                    ld.creator_id,
                    ld.tag_id,
                    SUM(ABS(ld.weight)) AS total_delegated
                FROM latest_delegations ld
                GROUP BY ld.creator_id, ld.tag_id
            ) delegated ON delegated.creator_id = u.id AND delegated.tag_id = t.id
        WHERE 
            u.id <> 0
            AND latest_rating.rating IS NOT NULL
        ORDER BY pnr.predicate_id, t.id, u.id
        LIMIT 10  -- Show first 10 voter records
    LOOP
        RAISE NOTICE 'Voter Debug - Predicate: %, Tag: % (%), User: % (%), Weight: %, Rating: %', 
                     rec.predicate_id, rec.tag_name, rec.tag_id, rec.username, rec.user_id, 
                     rec.final_weight, rec.rating;
    END LOOP;
    
    -- Debug: Show sample of what was calculated (first 3 records)
    FOR rec IN 
        SELECT car.predicate_id, car.aggregate_rating, car.number_of_ratings, car.weight_of_ratings
        FROM cached_aggregate_ratings car
        WHERE car.creator_id = cid
        ORDER BY car.creation_time DESC
        LIMIT 3
    LOOP
        RAISE NOTICE 'Sample result - Predicate ID: %, Rating: %, Voters: %, Weight: %', 
                     rec.predicate_id, rec.aggregate_rating, rec.number_of_ratings, rec.weight_of_ratings;
    END LOOP;
```
I've fixed the syntax error and added detailed debug statements to show individual voter weights and ratings. Now when the weighted delegation procedure runs, you'll see much more detailed output including:

## New Debug Output Added:

1. **Individual Voter Information**: Shows the weight and rating for each voter, including:
   - Predicate ID being calculated
   - Tag name and ID
   - Username and user ID
   - Final calculated weight for that user/tag combination
   - The user's rating for that predicate

2. **Sample Debug Output**: You'll now see messages like:
```
NOTICE: Weighted delegation procedure starting for creator_id 0. Found 5 predicates to update.
NOTICE: Voter Debug - Predicate: 123, Tag: science (1), User: alice (2), Weight: 0.1, Rating: 0.7
NOTICE: Voter Debug - Predicate: 123, Tag: science (1), User: bob (3), Weight: 1.3, Rating: 0.6
NOTICE: Voter Debug - Predicate: 123, Tag: science (1), User: carol (4), Weight: 1.6, Rating: 0.3
NOTICE: Voter Debug - Predicate: 123, Tag: politics (2), User: alice (2), Weight: 0.3, Rating: 0.7
NOTICE: Voter Debug - Predicate: 123, Tag: politics (2), User: bob (3), Weight: 1.2, Rating: 0.6
NOTICE: Voter Debug - Predicate: 123, Tag: politics (2), User: carol (4), Weight: 1.5, Rating: 0.3
NOTICE: Weighted delegation procedure completed. Inserted 3 new cached aggregate ratings.
NOTICE: Sample result - Predicate ID: 123, Rating: 0.4515, Voters: 3, Weight: 3.0
```

## What This Shows You:

- **Weight Calculation**: You can see how each user's final weight is calculated (1 + received - delegated)
- **Rating Values**: The actual rating each user gave for the predicate
- **Tag-by-Tag Breakdown**: Shows how weights differ per tag due to different delegation patterns
- **Final Results**: The aggregated result after all the weighted calculations

This will help you verify that:
1. The delegation weights are being calculated correctly
2. The latest ratings are being used
3. The weighted averages are computed properly
4. The averaging across tags is working as expected

The debug output is limited to the first 10 voter records to avoid overwhelming the logs, but you can adjust this limit if needed.

petermenegay: In the delegations table, what does weight_of_ratings mean?

GitHub Copilot: Looking at the code, `weight_of_ratings` is not a column in the `delegations` table. I can see from the schema in 002_tables.sql that the `delegations` table has these columns:

- `id` (inherited from user_created)
- `creator_id` (inherited from user_created) 
- `creation_time` (inherited from user_created)
- `receiver_id` - ID of the user receiving the delegation
- `tag_id` - ID of the tag for which the delegation works
- `weight` - Weight of the delegation (between -1 and 1)

However, `weight_of_ratings` **is** a column in the `cached_aggregate_ratings` table, where it represents "Summed weight of the ratings" used to compute the aggregate rating.

In the context of your weighted delegation procedure, `weight_of_ratings` in the `cached_aggregate_ratings` table stores the total sum of all the final weights that were used in the weighted average calculation. 

For example, if you have:
- User A with final weight 0.1 and rating 0.7
- User B with final weight 1.3 and rating 0.6  
- User C with final weight 1.6 and rating 0.3

The `weight_of_ratings` would be: 0.1 + 1.3 + 1.6 = 3.0

This gives you information about how much total "voting power" was involved in calculating the aggregate rating, which can be useful for understanding the confidence or representativeness of the result.

petermenegay: When I implement this in the database I am getting weight_of_ratings = 10 even though there are only 2 relevant users for the predicate I am looking at. Their weight should be at most 2. There are more users in the system than 2, however. Do you know why that might be the case?

GitHub Copilot: Looking at your weighted delegation procedure, I can see the issue. The problem is in how `weight_of_ratings` is being calculated. Let me trace through the logic:

The issue is in this part of the code:
```sql
SUM(total_weight) / COUNT(DISTINCT tag_id) AS total_weight
```

Here's what's happening:

1. **Cross Join Issue**: The procedure does a `CROSS JOIN` between `users` and `tags`, which creates a cartesian product - every user is paired with every tag.

2. **Weight Calculation**: For each user-tag combination, it calculates the user's final weight for that tag.

3. **Aggregation Problem**: Even if a user has 0 weight for a tag (because they delegated everything away or received nothing), they're still included in the calculation if they have a rating for any predicate.

4. **Multiple Tag Multiplier**: If a predicate has multiple tags, the same user's weight gets counted multiple times (once per tag), and then when you sum across tags and divide by the number of tags, you might not get the expected result.

Let me fix the weight calculation to only count users who actually have meaningful weights:
```


Made changes.

            -- Calculate weighted ratings per predicate
            SELECT 
                predicate_id,
                AVG(tag_weighted_rating) AS weighted_average_rating,
                COUNT(DISTINCT tag_id) AS number_of_tags,
                AVG(total_weight) AS total_weight,  -- Changed from SUM/COUNT to AVG
                AVG(total_voters) AS total_voters   -- Changed from SUM/COUNT to AVG
            FROM (
```
I made one change, but the real issue is deeper in the logic. Let me add some debug statements to help us understand what's happening with the weight calculations:
```


Made changes.

                WHERE 
                    ptl.tag_id = user_weights.tag_id
                    AND user_weights.rating IS NOT NULL
                    AND user_weights.final_weight > 0  -- Only include users with positive weight
                    AND EXISTS (
                        SELECT 1 FROM ratings r2 
                        WHERE r2.predicate_id = ptl.predicate_id 
                        AND r2.creator_id = user_weights.user_id
                    )
```
I found the issue! The problem is that the procedure was including users with zero weight in the calculations, and there was also an issue with how the total weight was being aggregated across tags.

I made two key fixes:

## Fix 1: Exclude Zero-Weight Users
I added a condition `AND user_weights.final_weight > 0` to only include users who actually have positive voting weight. Previously, users who had delegated away all their weight (resulting in 0 final weight) were still being counted in the calculations.

## Fix 2: Proper Weight Aggregation
I changed the weight aggregation from:
```sql
SUM(total_weight) / COUNT(DISTINCT tag_id) AS total_weight
```
to:
```sql
AVG(total_weight) AS total_weight
```

The issue was that when a predicate has multiple tags, the same users' weights were being summed across all tags, then divided by the number of tags. But this could still lead to inflated numbers if the cross-join was creating duplicate entries.

## Why You Were Getting 10 Instead of 2

Your `weight_of_ratings = 10` was likely caused by:

1. **Cross-join multiplication**: If you have 5 total users in the system and 2 tags on the predicate, the cross-join creates 10 user-tag combinations
2. **Zero-weight inclusion**: Users with 0 final weight were still being counted in some way
3. **Improper aggregation**: The summing across tags wasn't correctly accounting for the fact that each user should only contribute their weight once per predicate, not once per tag

With these fixes, you should now see `weight_of_ratings` reflecting the actual sum of the final weights of users who have both:
- A positive final weight for the relevant tags
- An actual rating for the predicate

Try running the procedure again and check the debug output - you should now see more accurate weight calculations that match your expectations.

petermenegay: It's still giving me weight_of_ratings = 10 after I implemented it. Do you have any other ideas for what might be going on?

GitHub Copilot: Looking at the code more carefully, I think I see the fundamental issue. The problem is in the aggregation logic when a predicate has multiple tags. Let me trace through what's happening:

1. **Cross Join Problem**: The `CROSS JOIN` between `users` and `tags` creates every possible user-tag combination
2. **Multiple Tags Multiplication**: When a predicate has multiple tags, each user's weight gets counted once per tag
3. **Averaging Issue**: Using `AVG(total_weight)` doesn't fix the underlying multiplication

Let me fix this by restructuring the query to calculate weights properly:I see the issue now. Let me take a completely different approach. The fundamental problem is that the current logic is too complex and is creating a cartesian product that's inflating the weights. 

Let me rewrite the weighted delegation procedure with a much simpler and more direct approach:
```


Made changes.

CREATE OR REPLACE PROCEDURE public.rating_calculation_procedure_weighted_delegation(id int4)
AS $$
DECLARE
    cid int4;
    predicates_to_update int4;
    processed_count int4 := 0;
    rec RECORD;
BEGIN
    SELECT creator_id
    INTO STRICT cid
    FROM rating_calculation_procedures rcp
    WHERE rcp.id = rating_calculation_procedure_weighted_delegation.id
    LIMIT 1;

    IF cid IS NULL THEN
        RAISE EXCEPTION 'Creator ID not found for procedure ID %', rating_calculation_procedure_weighted_delegation.id;
    END IF;

    -- Debug: Check how many predicates need updating
    SELECT COUNT(*)
    INTO predicates_to_update
    FROM get_predicates_with_newer_ratings_or_delegations(cid);
    
    RAISE NOTICE 'Weighted delegation procedure starting for creator_id %. Found % predicates to update.', cid, predicates_to_update;

    -- Calculate weighted ratings for predicates based on tag delegations
    INSERT INTO cached_aggregate_ratings (
        predicate_id,
        aggregate_rating,
        number_of_ratings,
        weight_of_ratings,
        creator_id
    )
    SELECT
        pnr.predicate_id,
        COALESCE(final_calcs.weighted_average_rating, 0)::numeric AS aggregate_rating,
        COALESCE(final_calcs.number_of_voters, 0)::int4 AS number_of_ratings,
        COALESCE(final_calcs.total_weight, 0)::numeric AS weight_of_ratings,
        cid AS creator_id
    FROM
        get_predicates_with_newer_ratings_or_delegations(cid) AS pnr
        LEFT JOIN (
            -- Calculate final weighted rating per predicate
            SELECT 
                predicate_id,
                CASE 
                    WHEN SUM(final_user_weight) > 0 
                    THEN SUM(rating * final_user_weight) / SUM(final_user_weight)
                    ELSE 0 
                END AS weighted_average_rating,
                SUM(final_user_weight) AS total_weight,
                COUNT(*) AS number_of_voters
            FROM (
                -- Get each user's final weight and rating for each predicate
                SELECT DISTINCT
                    r.predicate_id,
                    r.creator_id AS user_id,
                    r.rating,
                    -- Calculate user's average weight across all tags for this predicate
                    GREATEST(0, 
                        AVG(
                            1 + 
                            COALESCE(delegation_summary.net_received, 0) - 
                            COALESCE(delegation_summary.total_delegated, 0)
                        )
                    ) AS final_user_weight
                FROM (
                    -- Get latest rating for each user-predicate combination
                    SELECT DISTINCT ON (r_inner.creator_id, r_inner.predicate_id)
                        r_inner.creator_id,
                        r_inner.predicate_id,
                        r_inner.rating
                    FROM ratings r_inner
                    ORDER BY r_inner.creator_id, r_inner.predicate_id, r_inner.creation_time DESC
                ) r
                JOIN predicate_tag_links ptl ON ptl.predicate_id = r.predicate_id
                LEFT JOIN (
                    -- Calculate net delegation effect per user per tag
                    SELECT 
                        COALESCE(ld_received.user_id, ld_given.user_id) AS user_id,
                        COALESCE(ld_received.tag_id, ld_given.tag_id) AS tag_id,
                        COALESCE(ld_received.received, 0) AS net_received,
                        COALESCE(ld_given.delegated, 0) AS total_delegated
                    FROM (
                        -- Weight received from others
                        SELECT 
                            ld.receiver_id AS user_id,
                            ld.tag_id,
                            SUM(ld.weight) AS received
                        FROM latest_delegations ld
                        WHERE ld.weight > 0
                        GROUP BY ld.receiver_id, ld.tag_id
                    ) ld_received
                    FULL OUTER JOIN (
                        -- Weight delegated to others
                        SELECT 
                            ld.creator_id AS user_id,
                            ld.tag_id,
                            SUM(ABS(ld.weight)) AS delegated
                        FROM latest_delegations ld
                        GROUP BY ld.creator_id, ld.tag_id
                    ) ld_given ON ld_received.user_id = ld_given.user_id AND ld_received.tag_id = ld_given.tag_id
                ) delegation_summary ON delegation_summary.user_id = r.creator_id AND delegation_summary.tag_id = ptl.tag_id
                WHERE r.creator_id <> 0  -- Exclude system user
                GROUP BY r.predicate_id, r.creator_id, r.rating
                HAVING AVG(
                    1 + 
                    COALESCE(delegation_summary.net_received, 0) - 
                    COALESCE(delegation_summary.total_delegated, 0)
                ) > 0  -- Only include users with positive final weight
            ) user_weights
            GROUP BY predicate_id
        ) final_calcs ON final_calcs.predicate_id = pnr.predicate_id;
```
I've completely rewritten the weighted delegation procedure with a much simpler and more direct approach that should fix the `weight_of_ratings = 10` issue. Here's what I changed:

## Key Changes Made:

### 1. **Eliminated Cross Join Problem**
The original code was doing `CROSS JOIN` between `users` and `tags`, creating every possible user-tag combination. This was the main source of the inflated weights.

### 2. **Simplified Weight Calculation**
Instead of the complex multi-level aggregation, the new approach:
- Gets each user's rating for each predicate (latest only)
- Calculates each user's average weight across all tags for that predicate
- Applies the weighted average formula directly

### 3. **Fixed Weight Aggregation Logic**
The new logic:
- Calculates each user's net delegation effect per tag
- Averages the user's weight across all relevant tags for the predicate
- Sums only the final user weights (no double-counting)

### 4. **Direct Calculation Path**
The flow is now:
1. Get users who rated each predicate
2. For each user, calculate their average weight across all tags for that predicate
3. Apply the weighted average: `SUM(rating × weight) / SUM(weight)`
4. The `weight_of_ratings` is simply `SUM(weight)` - no multiplication

## Why This Should Fix the Issue:

Your `weight_of_ratings = 10` was likely caused by:
- **Cross-join multiplication**: 5 users × 2 tags = 10 combinations
- **Multiple counting**: Each user's weight was being counted once per tag, then aggregated incorrectly

With the new approach:
- Each user contributes exactly their calculated weight once per predicate
- No cross-join multiplication
- If you have 2 relevant users with weights 1.0 and 1.0, `weight_of_ratings` will be 2.0

The debug statements are still in place, so when you run this, you should see more accurate individual voter weights and a final `weight_of_ratings` that matches the sum of the actual voter weights for your predicate.

petermenegay: Ok, this problem appears to be solved now. However, there's still a small issue which concerns what happens when no one has delegated any weight yet. Right now what it does is calculates 0 for the result because, I think, it is defaulting to everyone having a weight of 0 before any delegations have been made. However, in this case,  the correct default weight for everyone is 1 and the calculation should yield the same result as the simpler procedure that finds the mean of the ratings.   

GitHub Copilot: You're absolutely right! The issue is that when there are no delegations yet, users should have their default weight of 1, not 0. The current logic is treating "no delegation data" as "weight = 0" when it should be "weight = 1".

Let me fix this by updating the weight calculation to properly handle the case where there are no delegations:
```


Made changes.

                    -- Calculate user's average weight across all tags for this predicate
                    GREATEST(0, 
                        CASE 
                            WHEN COUNT(delegation_summary.tag_id) = 0 THEN 1  -- No delegations = default weight of 1
                            ELSE AVG(
                                1 + 
                                COALESCE(delegation_summary.net_received, 0) - 
                                COALESCE(delegation_summary.total_delegated, 0)
                            )
                        END
                    ) AS final_user_weight
```
I've fixed the issue by updating the weight calculation logic. Here's what I changed:

The problem was in this part of the code:
```sql
-- OLD (problematic) logic:
AVG(
    1 + 
    COALESCE(delegation_summary.net_received, 0) - 
    COALESCE(delegation_summary.total_delegated, 0)
)

-- NEW (fixed) logic:
CASE 
    WHEN COUNT(delegation_summary.tag_id) = 0 THEN 1  -- No delegations = default weight of 1
    ELSE AVG(
        1 + 
        COALESCE(delegation_summary.net_received, 0) - 
        COALESCE(delegation_summary.total_delegated, 0)
    )
END
```

## What This Fixes:

**Before the fix**: When there were no delegations for any tags, the `delegation_summary` would have NULL values, and the AVG() would return NULL, which then got converted to 0 by GREATEST(0, ...), giving everyone a weight of 0.

**After the fix**: 
- If `COUNT(delegation_summary.tag_id) = 0`, it means there are no delegation records at all for the relevant tags
- In this case, we return the default weight of 1 for each user
- If there are delegations, we use the existing calculation logic

## Expected Behavior Now:

1. **No delegations exist**: All users get weight = 1, result should match the simple mean procedure
2. **Some delegations exist**: Users get their calculated weights based on delegation giving/receiving
3. **Edge case**: If a user delegates away all their weight, they still get weight = 0 (which is correct)

This should now give you the expected behavior where the weighted delegation procedure produces the same results as the mean procedure when no delegations have been made yet.

petermenegay: It's still giving me 0 even when no delegations have been made. Can you think of any additional reasons why that might be the case?

GitHub Copilot: Looking at the code more carefully, I think I see the issue. The problem is that there are still TWO places where the HAVING clause is filtering out users with positive weights, but the second HAVING clause is still using the old logic that doesn't account for the "no delegations = weight 1" case.

Let me fix the HAVING clause that's still using the old logic:
```


Made changes.

                WHERE r.creator_id <> 0  -- Exclude system user
                GROUP BY r.predicate_id, r.creator_id, r.rating
                HAVING CASE 
                    WHEN COUNT(delegation_summary.tag_id) = 0 THEN 1  -- No delegations = default weight of 1
                    ELSE AVG(
                        1 + 
                        COALESCE(delegation_summary.net_received, 0) - 
                        COALESCE(delegation_summary.total_delegated, 0)
                    )
                END > 0  -- Only include users with positive final weight
```
I found the issue! There was a second HAVING clause in the code that was still using the old logic and filtering out users incorrectly when there were no delegations.

The problem was that the weight calculation logic was updated in the SELECT clause to handle the "no delegations = weight 1" case, but the HAVING clause was still using the old formula that would evaluate to NULL (and thus get filtered out) when there were no delegations.

I've updated the HAVING clause to use the same logic as the weight calculation:

```sql
-- OLD (problematic) HAVING clause:
HAVING AVG(
    1 + 
    COALESCE(delegation_summary.net_received, 0) - 
    COALESCE(delegation_summary.total_delegated, 0)
) > 0

-- NEW (fixed) HAVING clause:
HAVING CASE 
    WHEN COUNT(delegation_summary.tag_id) = 0 THEN 1  -- No delegations = default weight of 1
    ELSE AVG(
        1 + 
        COALESCE(delegation_summary.net_received, 0) - 
        COALESCE(delegation_summary.total_delegated, 0)
    )
END > 0
```

Now both the weight calculation and the filtering logic use the same "no delegations = weight 1" rule. This should fix the issue where users were getting filtered out when no delegations existed, causing the final result to be 0.

Try running the procedure again - it should now correctly give each user a weight of 1 when there are no delegations, and the result should match your simple mean procedure.

petermenegay: This mostly works. The workflow is I create a predicate, tag it as part of some subject (science, politics, etc), and then give it a rating. As long as I do all that the default calculation works as it stands. But if all I do is create a predicate and give it a rating, it still reverts to 0 for the weighted result. It shouldn't do that. As long as the predicate has been created and rated at least once, the weighted calculation should take those who rated it, assign them a weight of 1 by default, and calculate the result (which will be the same as the simple mean of all the ratings). The fact that there are no tags to associate the weightings with doesn't matter. 

GitHub Copilot: I see the issue! The problem is that the weighted delegation procedure requires predicates to have tags (`predicate_tag_links`) to work, but you want it to also handle predicates that have ratings but no tags yet. In that case, it should just use the default weight of 1 for all users who rated it.

Let me modify the procedure to handle predicates without tags:
```


Made changes.

            FROM (
                -- Get each user's final weight and rating for each predicate
                SELECT DISTINCT
                    r.predicate_id,
                    r.creator_id AS user_id,
                    r.rating,
                    -- Calculate user's weight - if predicate has no tags, default to 1
                    CASE 
                        WHEN NOT EXISTS (SELECT 1 FROM predicate_tag_links ptl_check WHERE ptl_check.predicate_id = r.predicate_id) 
                        THEN 1  -- No tags = default weight of 1 for everyone
                        ELSE GREATEST(0, 
                            CASE 
                                WHEN COUNT(delegation_summary.tag_id) = 0 THEN 1  -- No delegations = default weight of 1
                                ELSE AVG(
                                    1 + 
                                    COALESCE(delegation_summary.net_received, 0) - 
                                    COALESCE(delegation_summary.total_delegated, 0)
                                )
                            END
                        )
                    END AS final_user_weight
                FROM (
                    -- Get latest rating for each user-predicate combination
                    SELECT DISTINCT ON (r_inner.creator_id, r_inner.predicate_id)
                        r_inner.creator_id,
                        r_inner.predicate_id,
                        r_inner.rating
                    FROM ratings r_inner
                    ORDER BY r_inner.creator_id, r_inner.predicate_id, r_inner.creation_time DESC
                ) r
                LEFT JOIN predicate_tag_links ptl ON ptl.predicate_id = r.predicate_id
```

```


Made changes.

                ) delegation_summary ON delegation_summary.user_id = r.creator_id AND delegation_summary.tag_id = ptl.tag_id
                WHERE r.creator_id <> 0  -- Exclude system user
                GROUP BY r.predicate_id, r.creator_id, r.rating
                HAVING CASE 
                    WHEN NOT EXISTS (SELECT 1 FROM predicate_tag_links ptl_check WHERE ptl_check.predicate_id = r.predicate_id) 
                    THEN 1  -- No tags = default weight of 1 for everyone
                    WHEN COUNT(delegation_summary.tag_id) = 0 THEN 1  -- No delegations = default weight of 1
                    ELSE AVG(
                        1 + 
                        COALESCE(delegation_summary.net_received, 0) - 
                        COALESCE(delegation_summary.total_delegated, 0)
                    )
                END > 0  -- Only include users with positive final weight
```
I've fixed the issue! The problem was that the weighted delegation procedure was only processing predicates that had tags (`predicate_tag_links`). When a predicate had ratings but no tags yet, it was being excluded entirely from the calculation.

## What I Changed:

1. **Changed JOIN to LEFT JOIN**: Instead of requiring predicate-tag links to exist, I made it optional with `LEFT JOIN predicate_tag_links ptl ON ptl.predicate_id = r.predicate_id`

2. **Added "No Tags" Logic**: I added a check for predicates without any tags:
   ```sql
   CASE 
       WHEN NOT EXISTS (SELECT 1 FROM predicate_tag_links ptl_check WHERE ptl_check.predicate_id = r.predicate_id) 
       THEN 1  -- No tags = default weight of 1 for everyone
       ELSE [existing delegation logic]
   END
   ```

3. **Updated HAVING Clause**: Applied the same "no tags = weight 1" logic to the filtering condition.

## How It Works Now:

- **Predicates with tags**: Uses the delegation-based weight calculation as before
- **Predicates without tags**: Assigns weight = 1 to all users who rated it
- **Predicates with tags but no delegations**: Assigns weight = 1 to all users (as before)

## Expected Behavior:

Now when you:
1. Create a predicate
2. Rate it (without adding tags)

The weighted delegation procedure should:
- Find all users who rated that predicate
- Assign each user a weight of 1 (since no tags = no delegations possible)
- Calculate the weighted average (which equals the simple mean)
- Return the same result as the mean procedure

This should fix the issue where untagged predicates were getting a weight_of_ratings of 0.